By on June 30, 2010

TTAC Commentator shores4now writes:

I have 111,000 miles on my 2000 Volvo S40 and it does not leak any oil. Have always changed the oil around 5000 miles. have never used synthetic on it before. I have heard I have too many miles to change over to synthetic. That it could cause my seals to leak if I switch over at this point. Have heard the opposite that if I don’t have any leaks that it will be fine. What do you think, should I switch over to a synthetic or a synthetic blend, or stick with what I have been using?

Sajeev Answers:
This might be the first time a Piston Slap question covered all the bases of a Piston Slap answer. Kudos to you! As such, you’ve reduced me to giving “yes” or “no” answers: so yes, I would make the switch. Because I did the same when I bought my Lincoln Mark VIII, at the young age of 117,000 miles. Immediately after, I had to replace the oil filter adapter gasket. Oops. But it’s a common, well-documented problem. I took the plunge fully knowing the consequence.

My advice: do your homework before committing to synthetic. Is there a common fail point that will need addressing on your Volvo? I suspect not, but a quick query (or the search feature) on VolvoForums.com might be in order.

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56 Comments on “Piston Slap: Vintage Swedish Meatball, Synthetic Oil?...”


  • avatar
    dingram01

    No. Do not make the switch. Your main seals will leak.

    If you were committed to making the switch, I trust you were considering at least doubling your oil change interval? I thought not. Then you’d only be wasting money on oil that costs double.

    I’m always interested to know: what makes you want to make the switch now?

    • 0 avatar
      baggins

      Honestly, I think this is unimportant in the grand scheme of car life. Faded paint, a thrashed interior, and a worn out suspension are more likely to cause you to scrap/sell the car vs engine wear.

  • avatar
    PeriSoft

    By what mechanism would switching from normal to synthetic at higher mileage cause leaks?

    • 0 avatar
      dingram01

      Synthetic oil has a smaller molecule size, which allows it to work its way past seals that work fine with dinosaur oil. I have personally seen this happen on my own car. Switching back to dinosaur oil cured the leak. This is common, not to say guaranteed to happen.

      Turbos and synthetics are nice because synthetic oil resists coking and sludging. But proper treatment of the turbo and frequent-enough oil changes (i.e., around 5k intervals with dino) work fine.

      [EDIT]: Another advantage to synthetic oil is improved shear resistance and better flow characteristics at cold start. However under normal conditions I think the advantage is not worth the added expense.

      I would, of course, run only synthetic in a car that specifies it from the factory, as in the BMW 540 I traded in last summer.

  • avatar
    shores

    i have just seen advertisement to get more mileage out of my car to run synthetic. I just recently had a Saab mechanic tell me that anything with a turbo should always run synthetic.

    • 0 avatar
      Ion

      The reason you want to run synthetic in a Turbo is because the synthetic not only flows better but it withstands heat better. Turbos get really, really hot because their spun by the exhaust and most of them are lubricated by the same oil the engine uses so they can cook oil.

      Even with synthetic burning a quart or so of oil is highly common in Audi/VW turbos. In fact that was a subject of another piston slap not too long ago.

  • avatar
    NN

    There is absolutely no reason to switch to synthetic at this point. It’s just a placebo unless you drive a true high-performance vehicle. There is no benefit, and if there’s any potential downside, then that makes the decision even easier. Keep the regular stuff in and just change the oil every 5k or less miles, and you’ll get just as much mileage out of the motor, IMHO. I’ve driven multiple cars into high mileage and never touched the synthetic stuff, and never once had any engine problems. I use generic Advance Auto oil and Fram or Purolater filters, and it all works just fine.

  • avatar
    1981.911.SC

    FYI You can switch back and forth anytime, any number of times!!
    I think the myth synthetic makes cars leak is from old Porsche guys. It will probably make little leaks bigger since it flows better.
    ANYWAY switch if you want to, or don’t……probably will not make any difference.
    If you really want the full write up, see Bob The Oil Guy’s web site.

    OH GOOD CALL… I second the turbo = synthetic notion.

    • 0 avatar

      +1….

      PS, I’ve got two turbo’d Audi’s, one at over 160k and the other at 100k, but making more than double stock HP, and neither burns a drop between changes….. I run synthetic in both ;)

      Lots of myths about oil….. almost as bad as spark plug “conventional wisdom”… Fortunately, There are many good internet sources of real data vs. the usual fanboi sites…. I thought this one did a decent job of describing differences without having to read a book on it… http://www.machinerylubrication.com/Read/1290

  • avatar
    Tissois

    I had an 1997 Hyundai Elantra. I switched to synthetic oil in the tranny and the engine: evrething went fine. I kept this car for 12 years.

  • avatar
    lawmonkey

    When I did fuels/lubricants testing in 02-04 synthetic made a noticeable and repeatable difference in engine wear over time. Our test lab had VW 1.8T engines and Ford’s F-150 V8 (5.3L?) engines running 24/7 under various simulated engine load programs. For what its worth, the effect was more noticeable on the 1.8T.

    This testing didn’t analyze switching oils midstream, however. I’m not sure why people have issues after switching, but it seems to be common. Check the forums – if the repair is minor, as Sajeev indicates it might be, consider going for it, especially if you intend to keep the car for a while.

  • avatar
    hoffa_lives

    Funny story, I had the opposite result of most of you when I switched to synthetic. I have a 88 Camry with the 2.5l V-6. The main seal was leaky, and I would lose half a quart of regular oil every ~500 miles. My mechanic recommended that I switch to Pennzoil Platinum, which is a full synthetic. I did, and the leak is now negligible.

    • 0 avatar
      Kevin Kluttz

      Because Pennzoil is the best oil. My ’01 Accord went 220,000 absolutely trouble-free miles switching back and forth between Pennzoil “dino” and Platinum. That’s all I need to know.

      “Sound your ‘Z’!

  • avatar
    snabster

    I switched over to syn on my saab at about the same point. If you’re running with a turbo, probably a good idea. If you’re not, just do more regular oil changes. No increase in seepage. My driving is all short, nasty, and brutal, so any extra protection I can get is good. Change it 2-3 times a year at 3500 mile mark.

  • avatar
    sastexan

    Sewell Lexus in Dallas is recommending / mandating its owners of new RX350s go to full synthetic (and of course passing on the increase in cost), but reducing the change interval. I just don’t see the benefit in a brand new, NA car engine. The service people claim that factory fill was synthetic. My mom’s RX had first oil change at 5k with dino, but for the 10k service they want to switch to synthetic and push the interval to 10k. I can’t believe the filter is up to the task. What does the best and brightest think?

    • 0 avatar
      crc

      Depends on the filter. I don’t think I would push a standard filter past 6k miles. That’s where a Purolator Pure One or Bosch Extended comes in handy.

    • 0 avatar
      Russycle

      MINI claims their synth(Castrol) is good for 15K, but after reading posts from guys who’ve had their oil analyzed and I wouldn’t go longer than 7500, no matter what filter you’re running.

      I drove a 93 Escort to 200K on dino oil, changed every 5000 miles or so, and the compression was nearly at brand new spec when I had it checked. I’d stick with dino and keep up the regular changes, why take a chance on leakage for negligible benefits?

    • 0 avatar
      segfault

      I think you mean increase the change interval, or reduce the change frequency.

    • 0 avatar

      Sludge risk…. Dino oil sludges up easier, and from other class action lawsuits (can’t remember if that engine was in it or not), the oil passages appear to be too small. Synthetic significantly reduces that risk. Unless you like buying new engines due to sludge, its cheap insurance isn’t it?

  • avatar
    crc

    FWIW – Synthetic oil doesn’t make seals leak. If a seal leaks it needed to be replaced anyways.

  • avatar

    In my 2001 S60 (normally aspirated), I switched at 90k or so to a blend, with intervals between 4-5k. No leaking. In fact, the car never used any measurable oil in its life. Full synthetic seemed a waste however.

  • avatar
    cdotson

    The leaky seals thing may be myth or there may be some traction there. The mechanism I’ve heard is that old engines have some degree of sludge-like deposits in the oil system that will break loose and flush out after switching to synthetic (or doing an oil system flush; the thought of those always scared the bejeezus outta me). The old seals, minus their adjacent sludge-plugs, now leak.

    Fact or fiction I can’t say; but that mechanism seemed plausible. Long time ago I switched my near-100k mile Dodge 318 from the PO’s Jiffy Lube-worst over to synthetic, but I went to Castrol Syntec because it has a higher ash content and was supposedly less likely to allow leaks by the above-postulated mechanisms. After years on Syntec I ran Mobil1 in it for a while (was using Mobil1 in my new truck by then) and developed weepy valve cover gaskets, but it wasn’t a bad “leak” and it may have been coincidental (or I was just looking for it). Truck was over 140k by then anyway.

  • avatar
    werewolf34

    What about the extended life / high mileage oil formulations?

    Any validity in using them?

    Asks the guy with a 133k mile car

  • avatar
    Steven Lang

    Here’s the synopsis…

    Conventional oil every 3k to 5k is absolutely fine. Most engines that are not abused will last well past the 230k mark with regular dino juice.

    NOTE: The author owned a Camry Coupe for 12 years and 239k. It’s still on the road with close to 300k. Nothing but dino oil and a common/cheap filter every 5k.

    Synthetic works particularly well if you do a lot of driving (20k+). My cars average 18k and 28k respectively. For these, I use the top of the line filter (Mobil 1) and full synthetic BUT I change the oil every 10k or six months. I also top them off every few thousand miles which is very beneficial.

    Cost wise it comes out to about $20 per oil change. But I take advantage of commercial discounts when they’re available. For a DIY the cost will be around $30.

    If it were me, I would stick with dino oil changes. There are a thousand things that can go wrong other than engine lubrication, and your money would be better invested in getting OEM parts when they are needed. Especially if you plan on keeping it for another ten years.

  • avatar
    FleetofWheel

    One of the big oil companies had an ‘ask an engineer’ call-in a few years ago.

    He affirmed that synthetic oil does not lose it lubricating properties for a long time but said dirty by-products from combustion will still accrue.

    So depending on the ‘residue’ carrying capacity of the oil filter, it seems like using regular oil can be cleaner with it’s more frequent changes.

  • avatar
    alex_rashev

    There’s absolutely no harm with switching to synthetic (or back). I have done quite a bit of reading on this, and switched a lot of engines to synthetic, from brand-new cars to 35-year-old Pontiac V8’s. As long as you use correct weight, you’re fine.

    The reason why people notice their cars leaking oil after synthetic oil switch is because they look. If the leak wasn’t there before, it won’t be there after the switch.

    If you do a lot of driving in cold/hot climate, if you tend to skip oil changes, or if you drive the everliving hell out of your car, get synthetic. Better fuel economy and extended intervals will make up for the price difference, and added reliability is a bonus. Make sure you use a good oil filter.

    On the other hand, most modern cars end up on the junkyard due to cracked dashboards, ripped seats, and faded paint, rather than engine failures. If you just want to drive back and forth, change regular dino oil every 10k miles or so, and you’ll be fine.

    IIRC GM extended oil change interval from 3 to 6K miles after introducing HEI ignition. That’s still in the era of carburetors and crappy metallurgy. No reason why a modern car wouldn’t survive 10K interval on discount oil and filter.

  • avatar
    mikey

    I’m from the “if it ain’t broke,don’t fix it” school of thought. The guy gets 111K ,no leaks it runs great,why f–k with it?

  • avatar
    newcarscostalot

    I suppose I’ll put my two cents in. I have had new and old vehicles with low and high (and sometimes unknown!) mileage. I have used synthetic and regular on the same vehicles depending on how much I wanted to spend. I never had an issue either way. I do however always change my oil no later than 3k miles or 3 months, whichever comes first. I have used Castrol GTX and Fram oil filters myself and seen my own and other vehicles last past 130,000 miles without issue. These days, synthetic oil is not much more costly than regular, so price should not be an issue. So, it depends on what you want to do. I hope that helps.

  • avatar
    dingram01

    Just to repeat my experience for those of you who apparently have no reading comprehension: synthetic leaked past seals in one of my previously dino-oil cars. Switching back to dino eliminated the leaks.

    I do all my own work — every oil change I’m under there looking at everything. I’m not making it up. Neither are the zillions of others who’ve experienced the same thing.

    • 0 avatar
      alex_rashev

      I would like to know which seal was leaking oil. Are you sure it wasn’t the filter or oil plug washer? :)

      Cold synthetic oil does flow quite a bit better than regular oil of the same top viscosity index (hence you usually see 0w-30 synth vs 5w-30 or 10w-30 dino). When hot, it’s the same stuff. So the only way you can get an already existing leak to leak more is when the car is cold, which leaves the oil plug washer as the only failure point. When hot, any dino oil will flow better than cold synth oil, so they’ll leak the same.

      I don’t see any manufacturers recommending against synthetic oil (except maybe Mazda and Rx-8, which burns oil by default). If there would be any proven potential complications from a change, you’d definetely hear about people having their 100K mile powertrain warranties voided due to synthetic oil switchover – no manufacturer wants to pay through the nose for seal replacement caused by actions of a careless customer. But apparently, manufacturers don’t care, because it’s not a problem. Follow the money, not the rumors ;)

    • 0 avatar
      dingram01

      It was the main seals, front and rear, as I noted IN THE VERY FIRST COMMENT ON THIS TOPIC. I am sure.

      Good lord.

      Once again, I repeat. Synthetic oil has smaller molecules than dinosaur oil. This is the reason it often leaks in cars that didn’t leak with dino oil. It’s a fact, not fiction, although it is not guaranteed to happen to every car.

  • avatar
    Kevin Kluttz

    Mmmmmmm….Whom to believe here….
    Looks like we all just need to stay with whatever we’re doing and whatever we’re using, if it makes us happy!!

  • avatar
    sastexan

    If you REALLY want to know when to change your oil, send it off for an analysis. I’ve done it a few times, and I have learned that I can run my 2.5L Duratec V-6 on Mobil 1 and stock Motorcraft filter over 6k with no detrimental results. I’ve been running Mobil 1 since its 3rd oil change at 12k miles – 12 years and over 120k miles ago.

    As far as the type of oil, read the oil analysis folks’ FAQ here: http://www.blackstone-labs.com/which-oil-to-use.php

    http://www.Bobistheoilguy.com is another great resource.

  • avatar
    vento97

    One word – German Castrol (a.k.a. Castrol Syntec 0w30 (must have the “Made in Germany” wording on the label)…

    Turbocharged engines should use synthetic. Period. End of Story. Unless you want your turbo to die an early death to the tune of $1500+ in replacement costs. In the case of the engine, even higher $$$$…

  • avatar
    beken

    I made the switch and all’s well. I have a 25 year old Pontiac Fiero. I’ve owned the car since new, and it was my daily driver for the first 20 years. When it was no longer my daily driver and my wife allowed me to keep the car, I decided on synthetic oil so I wouldn’t have to worry too much about changing the oil every 6 months regardless of mileage. The car has 200,000 kms (about 120,000+ miles) and there were signs of oil seepage from the head gaskets. But after I started using synthetic oil, the seals seem to have dried up. No leaks. Plus I don’t have to change my oil as often. I was well aware of the risks (that more oil would leak out), but was planning on a full restoration anyways. After a few years of synthetic, I recently had the engine checked over and the mechanic informed me the engine was still very good and I should spend my money restoring the suspension instead.

  • avatar
    Geo. Levecque

    Here in Northern Climates I have used Synthetic on a older Camry, helps with easier starting without using the Block heater in the Winter, but it’s twice the cost of conventional oil, so on my RAV4 I use only the conventional oil and change it at 5/6 thousand Kms, its cheap insurance.

  • avatar
    lilpoindexter

    I think the story about getting leaky seals after running dino oil for a long time was created by the same people that invented the easter bunny and sasquatch.
    I put synth oil in my rarely driven Miata, and yes, it dribbles a little, but I attribute that to extended periods of storage of the car. By putting synth oil in it, the lifters don’t leak down and make a disturbing racket on the rare occaision that I actually start the car up.
    I also have a daily driver POS protege that has a fair amount of blow by, which seems to be helped by running thicker synth oil.
    Why not just try the synth oil and see what happens, you can always switch back if you don’t like it.

  • avatar
    shortthrowsixspeed

    I took my car in to my favorite shop for it’s regular oil change and asked for the basic oil change. I was told that they did away with the “basic” change and either had a G-Oil or Amsoil change. I’d never heard of G-oil, so I googled it. Apparently it’s a Green Earth Technology product that is 100% biodegradable motor oil made from animal products. It’s supposed to be certified by American Petrolium Institute and is endorsed by Le Mans racing. I could not, however, find any reviews or anything.

    Anyone know anything about this?

    • 0 avatar
      Gardiner Westbound

      Sounds like a scam. You may need to find another shop.

    • 0 avatar
      John Horner

      G-oil is a legitimate product. They are using animal fats as the starting point to make a synthetic oil. Fully tested to API standards. I haven’t tried it myself and am not recommending it per se, but it is NOT a scam.

    • 0 avatar
      shortthrowsixspeed

      well, as for me I’ve had the “G-Oil” in my 2003 mazda protege for about a week. nothing’s died or blown up. it doesn’t run appreciably better than it did before either though. At first I thought it was messing with my gas mileage, but my wife borrowed my car one day and she’s always blasting the a/c (me i prefer open windows). so that was probably it. if anything notable happens, i’ll note it.

  • avatar
    Ion

    The switch to synthetic alone will not make your seals leak. You can also switch back to a conventional after you’ve used a synthetic. Synthetic is really at a heart, conventional that is treated with additives. Both Synthetic and conventional start out life as regular crude oil.

    What I would however recommend in your case is a high millage oil (for example Valvoline Max life) Or a can of Engine Restore at every oil change.

  • avatar
    Gardiner Westbound

    My best information is synthetic oil makes financial and other sense only for turbocharged engines, true performance vehicles and vehicles operated in extreme temperature climates, very cold or very hot.

    Synthetic oils are classified into three groups: Group III, Group IV, and Group V.

    Group III synthetics, manufactured from less costly petroleum base stocks, are hydrocracked to remove impurities until they attain synthetic oil properties. The oil and additive companies, which control the domestic classification system, deemed them synthetic – but only for the North American market. Elsewhere they are classified as premium motor oils. Almost all domestic synthetic motor oils are Group III.

    Group IV polyalphaolefin (PAO) and Group V (Ester) synthetics are manufactured from expensive synthetic base stocks and are of much higher quality. They are the only true synthetics. Strict European specifications, set by automakers, require that all synthetic motor oils are Group IV or above. They include Elf (aka Total Quartz), Motul, Germany’s Castrol Syntec 0w30 (aka German Castrol), and Pentosin.

  • avatar
    calvin1234

    If you decide not to switch to a synthetic try Motorcraft’s synthetic blend. That is what I use and change it at 5K like any dino oil.

  • avatar
    alfabert

    I’ll throw in my data points and/or superstitions:

    * I lost the oil pump (due to a SEVERE pavement change) in an ancient VW Rabbit. But I didn’t know it, and drove it for 3 more miles without oil pressure… But it was running synthetic as it had since the first oil change, and the engine survived without damage (whereas the rest of the car was junk, or rust, whichever came first.)

    * After the above near-death experience, I’ve run synthetic in everything I’ve owned, new or used, ever since. It’s so wonderful, it kept the Alfas from rusting…

    * I changed over at 27K, 60K and 73K miles to synthetic on various Volvos; the two higher mileage ones never leaked; but the lowest mileage one always leaked thereafter just enough to be annoying.

    * A friend changed over to synthetic on a 110K mile Acura, and promptly had it blow oil out through every available seal…

    * And the mechanic who replaced the failed seals from this leakage spectacle, already subscribed to the “don’t change after 10 years and/or 100K miles”; and he’s finally persuaded me of its correctness as well.

    YMIGTV (your mileage is guaranteed to vary)

  • avatar
    Rada

    I was changing tranny fluid recently (syntetic Toyota Type T-IV), and that thing is nasty. It leaks from everywhere. Even a tightly closed bottle is covered in the cherry-colored liquid shortly after wiping it clean.

    I had to use full force of my body to tighten the drain plug so that it does not leak.

  • avatar
    John Horner

    This question gets beaten to death at places like bobistheoilguy.com.

  • avatar
    texan01

    I changed my Explorer over to synthetic at 120,000 miles and 7 years old with nary a leak, until it had 230,000 miles on it.

    I didn’t dream of switching the Chevelle over to it until now as the 30 year old seals had no hope of actually sealing anything, now that its got new gaskets on the engine I might do it.

  • avatar
    SVT48

    I believe there is some truth to the increased leaking from synthetics. A while back I changed an older Toro lawnmower over to Mobil1 because I thought it would be better for the Briggs & Stratton engine when I used it to mow a steep hillside that might reduce the effectiveness of the crude oil distribution system. Net result was significant leakage from numerous gaskets. As with other examples, only anecdotal evidence but it all seems to point toward synthetics finding (or increasing) leakage at weak seals and gaskets. On the turbo front, my experience with Ford Probe/Mazda 626 turbo and aftermarket 260Z turbo indicates that the primary issue with oil “coaking” is caused by people who don’t know enough to let the turbo cool down at idle for a minute or two before shutdown. Pulling in to a rest stop after running for hours at 70+ mph and immediately shutting down the engine allows heat to soak from the exhaust side of the turbo into the bearing and cook the oil. Synthetic may help some but I’m not sure it will totally prevent this issue.

  • avatar
    Advance_92

    On my own turbo car (now six years old) I switched to synthetic and oil just started to vanish. There were no puddles in the garage so I suspect it was getting by the rings and burning up in the cylinders. I switched back to regular oil three years ago and have had no more disappearing oil.

    After 93,000 miles (somewhere over 95 by next week) and with no oil loss or clouding I have to put myself in the ‘not broke, don’t fix it’ category.

  • avatar

    My ’99 Volvo S70 runs synthetic. It has 213k on the odo. I purchased it at 200 k and I didn’t own it when it switched from conventional to synthetic oil. That said, it doesn’t leak a drop, and I’ve been through two oil changes since I owned it. It does burn some, and I top it off with a quart mid-cycle. My mechanic tells me it’s normal with these cars, and it’s a bit of pain to burn the expensive stuff, but overall it’s worth it. We have a real winter where I live and I didn’t use a block heater… the car cranked just fine every time. Around here they call synthetic “liquid block heater.”

    Basically, my engine is the 5-cyl version of the 4-cyl that goes in your S40, so I imagine the seals are similar, but there may be some serious decontenting and beancounting on the S40 so do your research.

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