By on May 6, 2013

TTAC Commentator Halftruth writes:

Sajeev,

I am in the market for a new mid size truck. I have been looking at Tacomas both new and used and came across a used one at a decent price. Thing is, the owner states that “purchased new and immediately changed all fluids to synthetic from the oil to the rear diff”.

I am not crazy about this as I have heard of nightmares from folks going to redline, purple stuff etc etc for a better (shift, mpg whatever). Why dont folks leave well enough alone? What is your take on this???

Sajeev answers:

Considering many vehicles run synthetic (motor) oil from the factory and even more run semi-synthetic stuff, I’m pretty much indifferent.  Making the switch in the first few years of ownership isn’t gonna hurt anything, provided you use the right weight/type and there isn’t a huge warning from the manufacturer about deviations from the factory stuff. (Subaru, Ferrari, BMW have all done this in the past, IIRC.) Hell I switched to synthetic (engine) oil in my Mark VIII when I bought it at the ripe old age of 117,000 miles!  Aside from one common gasket fail point, I had no problems.

So why not switch to a full synthetic for most vehicles?  You gotta love your ride for the next 10-20 years, that’s why not. That said, I switched my Ford Ranger over to Mobil 1 after 6,000 miles…so I guess I’m in it for the long run, too.

Perhaps synthetic rear axle fluid is also better, but I’ve switched before and never noticed a difference.  But, on an older vehicle, if you’re going in there for something else…might as well make the switch.

Transmissions?  That’s where the shit gets real.  The sheer number of fluid requirements for gearboxes (mostly automatics) is more than a little horrifying.  You gotta be REAL careful here. Any aftermarket synthetic oil you choose had better be compatible with the factory fluid. So do your homework: like a Q&A session with an answer right from the horse’s mouth.

Send your queries to sajeev@thetruthaboutcars.com. Spare no details and ask for a speedy resolution if you’re in a hurry…but be realistic, and use your make/model specific forums instead of TTAC for more timely advice.

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25 Comments on “Piston Slap: Wither Synthetic Oils?...”


  • avatar
    NormSV650

    I switch to synthetic for the longer drain interval for motor oil. The synthetic stuff does make manual transmission easier shifting in colder climates. Some independent differential can get chatty and whine and synthetic gear oil does quiet them down and offers different weights with no significant effect on fuel economy.

    Then at other end of the lubricant spectrum are zealot Amsoil users who swear by every Amsoil product and have proof done by none other than Amsoil themselves. To find out they are personally sell the stuff too. They usually try to sneak onto vendor paying automotive forum without paying vendor fees but are soon uncovered advertising their wares.

    • 0 avatar
      OldandSlow

      Amsoil does sell a variety of oils, one of which is Z-Rod, which contains ZDDP additives for older, pre-catalytic converter, push rod engines.

      • 0 avatar
        DeadWeight

        “Then at other end of the lubricant spectrum are zealot Amsoil users who swear by every Amsoil product and have proof done by none other than Amsoil themselves. To find out they are personally sell the stuff too. They usually try to sneak onto vendor paying automotive forum without paying vendor fees but are soon uncovered advertising their wares”

        It’s not just Amsoil vendors who do this, and it’s annoying as hell.

        Royal Purple (it must be good since it’s dyed purple /sarc) and some other labels/brands are perpetually hawked by carnival barkers on automotive forums the world wide web over, in fevered pitches extolling the mythical-HarryPotteresque properties of their magical elixirs and potions.

        I am not saying that Amsoil doesn’t have some good products, but I am saying that the gap between their alleged superiority vs other API SM, JASO and/or ILSAC labeled products is more hype based on marketing than reality born of hard facts.

        As for Royal Purple, like stated above it’s approved in terms of meeting credible standards, but the whole purple dye marketing schtick sadly reminds me of Marvin’s Mystery Oil’s cheesy angle.

  • avatar
    gtemnykh

    Recently went over to all synthetics on my MPV for the front and rear diffs and the transfer case. The car is a ’98 and had 158k at the time. I applaud the seller of the car that you’re interested in for switching right off the bat. That’s a good $120+ for the fluid alone, and money well spent IMO.

    I’ve ran synthetic in the engine before, but my hydraulic lash adjusters sound happiest with good old high mileage 10w30.

  • avatar
    OldandSlow

    Likewise, I use full synthetic in both the engine and manual transaxle, mainly because I feel they are superior when cold weather hits.

    On my 71 VW Bus, which runs the oil in the 225F to 240F range in the heat of summer – I use a synthetic that has Zinc, Phosphate – ZDDP – added. Full synthetic holds its viscosity range better over the life of the oil change in these conditions. Lesser quality multi-weight oils break down sooner when torched.

    Let me add that I do my own oil changes and a high grade, full synthetic looks and feels so much nicer than non-synthetic after it has been tortured.

  • avatar
    walleyeman57

    I am a pretty big advocate of Mobil 1 for the engine oil but I stick with factory trans fluid. This habit comes from my Dodge Mini Van days. We have had two that made it well past 150K without issues when sold when many Dodge trannys were failing with less than 100K. A mechanic friend suggest that we only stay with factory fluid and change every 30K.

    On our current vehicles, the 03 Honda Pilot has had Mobil 1 since 3K and is now at 270K miles with no issues. Our 04 Sienna is Mobil 1 since 60K (purchased used) and is now at 340K miles also with no issues-although she is getting a little noisy on real cold start-ups.

  • avatar
    IHateCars

    Go to any automotive forum and the most heated/passionate/crazy threads have to do with oil…conventional vs. synthetic, brand, change intervals, etc… I think those exchanges get far more heated than those about religion, politics and guns combined.
    In any event, I’ll use whatever synthetic happens to be on sale at the moment…mainly due to the cold weather we get up here. All else being equal, I find that maintaining the proper change interval makes more of a difference than brand/type of oil, contrary to the marketing hype.

  • avatar
    chainyanker

    Along with the synthetic switch, did the previous owner also inflate the tires with designer nitrogen and replace all the wiring with Monster Cable? The truth is you can get hundreds of thousands of miles out of a car with no oil related problems using just regular old oil. It depends more on the car and the drivers habits.

  • avatar
    dancote

    Pretty sure you meant whither.

  • avatar
    Steven Lang

    The only variation I do these days is a 10k oil change interval using Mobil EP and either a Mobil EP filter or the Bosch Long Life filter.

    For me it’s a matter of convenience. I can keep all my car maintenance on a 10k schedule which allows me to more easily take care of the things that go beyond motor oil.

    If you keep your eyes out there for deals at the Bob Is The Oil Guy web site, your running costs will be comparable to most conventional 5k oil change intervals.

    Hope this helps…

    • 0 avatar
      davefromcalgary

      Ditto on this.

      I changed my 270,000 kms 02 Alero over to synthetic 10W30 about 100,000 kms ago, usually using just whatever is on sale at Canadian Tire, and a 15,000 kms (9300 miles) oil change interval. The car runs great to this day, and at each oil change I get 4.5 L back from the 5 I put in, which is actually a slight improvement over conventional.

      Once nice thing about the ECOTEC engine is that I can change the oil filer at smaller intervals with the engine full of oil, seeing as it has a top loading cartridge style oil filter.

      Since I am an apartment dweller, I made the change mostly out of convenience and it works pretty well. No problems to report.

  • avatar
    Conslaw

    I switched to synthetic oil in two cars, and both were totaled in accidents before they hit 70k miles. From this I can only gather, that synthetic oil attracts other vehicles using some weird electromagnetism that has yet to be explained by science. Run away.

  • avatar
    gslippy

    In my former Scion xB1, I switched the manual transmission fluid to synthetic with great results; it became much easier to shift in cold temperatures. A flatter viscosity-temperature curve is a big advantage of synthetics.

  • avatar
    stottpie

    you should switch to synthetic as soon as reasonably possible for all your oil.

    conventional oil is way too thick when it’s cold, which is why you can only get 10wX +, while synthetic can be had in 0wX

    if you’ve ever felt motor oil at room temperature you’ll notice how thick it is. that is not good for cold engine start up. that’s the major reason why synthetic is better, at operating temperature they both perform similarly enough.

  • avatar
    eggsalad

    What a timely article! I’m about to do my 10,000 mile oil change this morning!

    I’d like to say that I use Mobil 1 EP because it’s great for my engine, or because it provides it provides greater protection in the Las Vegas heat, but the real reasons are cheapness and laziness.

    Toyota recommends 5k changes for my Scion xB1. Using conventional oil, I would spend $10+ on oil and a $5 (Genuine Toyota via eBay) filter. With the Mobil 1, I spend $20 for the oil and change the filter half as often, so it’s actually cheaper to use synthetic!

    I’m also pretty lazy. I’m sure I’ve done over 200 oil changes on my personal vehicles over a 30+ year driving career, and frankly, there’s no joy in it any more. It is a chore, like vacuuming. Sure, I take pride in my work, but I can’t say I look forward to doing an oil change.

    As for transmissions… I have no idea what happens in the world of automatics, but with conventional oil, I would change manual transmission oil every 30k. Redline Oil has an MTL that meets the specs that Toyota wants, and I consider it a “lifetime” fill. Again, it’s a no-brainer to spend $30 on the good lube and ignore it for the next 100k or more.

  • avatar
    blockmachining

    Another important consideration is that oil extracted from the earth (conventional motor oil) is one weight only….say 30w or 50w….whatever that well is producing. The oil engineers have to add polymers to make the oil multi-viscous (like 10W-30). These polymers link up/join and this is the black goo you see on top of the heads and clogging up oil galleys and oil jets. With fully synthetic oil, there are no polymers. You can tear down an engine with 150K miles on the odometer and the engine looks just like it did when it was first machined at the factory. The oil galleys and jets still have the same dimensions as when they were machined. The only discolorization occurs at the top of the combustion chamber where the greatest heat is located at. With the conventional oils, the more restrictive oil galleys and especially the partially or completed clogged oil jets do a lot of damage. During a cold start, if the main bearing’s oil jet is clogged with these polymers, there will not be a jet of oil sprayed up onto the cylinder walls which prevents piston skirt slap and the resulting wear on both the piston skirt and cylinder wall. With conventional oils….once the oil warms up, the rotating crankshaft will splash enough oil up on the cylinder walls to prevent this accelerated wear event. Synthetic oils are the way to go.

    • 0 avatar
      OldandSlow

      On the other end of the temperature scale – A good Group IV (PAO) based synthetic will maintain its high temperature viscosity performance for many more miles than an old-school oil or paraffin based Group (II) multigrade.

      The polymers in some old-school 10W-30 dino oils may degrade before the end of the 3,000 mile interval to lube as well as a single viscosity 15 or 20 weight oil at high temperature.

      I wouldn’t run a turbo engine on anything but a Group (IV) synthetic.

      Keep in mind that not all synthetics use a Group IV polyolefin (PAO) polymer based stock.

      For example: Amsoil XL uses a Group (III) base stock derived from Group (II) oil, while their Signature series uses a Group (IV) stock – probably purchased from Mobil.

    • 0 avatar
      wmba

      @ blockmachine

      With knowledge like this, you should apply for a job at Mobil R&D.
      They will be astounded at your knowledge of straight viscosity oil coming out of the earth. I guess refineries are superfluous. Who knew polymers agglomerated and clogged oil jets? Unless sludge is the common name.

      The engine manufacturers go out of their way to avoid crankshafts “splashing” oil. It just is not done. That exacerbates windage and oil foaming, so is avoided like the plague. The last engine with oil dippers on the con rods (not the crank) was the ’53 Chev 235 six.

      I’ve owned cars since 1967 and always used regular oil. Never had sludge, not once or ever, but have avoided short trips with cold engines. Never had an oil consumption problem either.

  • avatar
    Timothy

    I’ve always stuck with MFG suggestions. Passat was Mobil 1 502.11 Fully Synthetic. Ford is 5-30 Synthetic. I figure the MFG’s have spent millions of dollars in R&D on the drivetrains for these cars, following their recommendation just makes sense.

    • 0 avatar
      stottpie

      for the most part i’d agree with you.

      however, consider that 5w20 might give you more fuel economy and HP, but maybe 5w30 will provide better wear protection.

      i’m not saying that’s exactly the case, but in general thinner oils give more fuel economy, while not offering as high of wear protection.

  • avatar
    WaftableTorque

    I think it’s a car enthusiast’s curse to do more than the minimum necessary. If you look up the owners manual, many will ask you wipe your leather seats with a damp cloth and clean the interior with soapy water. We can’t leave well alone and buy the latest leather cleaner and separate conditioning lotion, and UV conditioning protectants for interior plastics. Synthetic oil is the same: technically superior in circumstances that our vehicles might not be subject to, but we do it anyway for peace of mind.

  • avatar
    corntrollio

    “Making the switch in the first few years of ownership isn’t gonna hurt anything”

    Is there any evidence that switching from dino to synthetic later in the vehicle’s life causes problems?

    I seem to remember some theory about seals becoming less swelled up when using synthetic, causing leaks, but it sounded BS.

    The Amsoil/Royal Purple non-sense on many forums is annoying, as people stated above. Many of them are obvious shills. No one’s ever able to show how those oils meet certifications or why they’re better, it seems.

  • avatar
    nrd515

    I’ve used Mobil 1 for over 30 years, changing it twice a year. The only one of my engines that I was able to look at was my ’93 Grand Cherokee’s 4.0, and it was amazingly clean with 70K on it. The valve cover gasket cracked or split and had to be replaced when it started trickling oil out the back end of the cover. I saw a friend’s 2001 GMC 5.3′s innards when he put a cam in it, and it was amazingly clean with over 150K on it. The cross hatch marks were still on all the bores, and everything looked to be in spec, so a new timing chain, valve springs, and water pump were put on and off it went. I don’t think the cam change was worth it, but he’s happy with how it runs.

  • avatar
    300zx_guy

    on a slightly different subject, what a about oil changes for a car that doesn’t rack up the miles very quickly, say 4-5k mi/yr. Do you change every six months? every year? Does conventional vs synthetic make a big difference in this case?

    • 0 avatar
      corntrollio

      Definitely every year at minimum. 6 months wouldn’t be terrible.

      The issue is that if you’re not getting up to operating temperature regularly, you’ll end up with more moisture in the oil and things like that, so you may still need to get the oil changed.

      If you want to go for the year, synthetic is probably better, but the operating temperature issue is more important. I’ve had daily drivers where I drove approximately this much, but I regularly got up to operating temperature, so I didn’t worry about it too much.

      If you really wanted to find out, you could get an oil analysis done.


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