Piston Slap: Sonata Salad Oil, Thoughts on Lubrication

TTAC reader Chris writes:

Regarding my 2007 Sonata 2.4L, 5-speed: can I use 0W-20 in place of 5W-20 and keep the warranty intact?

Sajeev responds:

Why? Most engines can handle a small step up/down in viscosity without catastrophic failure, but doing this does not compute. 5W-20 is already lightweight stuff. If fuel economy is your concern, switch to synthetic: its molecules are smaller than dino oil and offer more protection to boot.

Odds are a cost-engineered Hyundai mill doesn’t have the tolerances and lubrication needs (at 7500 rpm) of exotic engines that demand 0-grade oil. And if you live in warmer climates, you are likely to cause more engine wear for no good reason, causing problems after that 100,000 mile warranty runs out.

Don’t do it. Unless our B&B has something to the contrary for Hyundais in particular, of course.

JG writes:

Remember those E46 M3 BMW tachometers that had a variable redline that moved up as the engine and oil came up to temperature? Those were cool. I think when you first started the car, the maximum suggested revolutions were around 5000.

For people who don’t have this sort of feature, we can look in our owner’s manual and find no information whatsoever with regards to how long to let the engine run before we can really boot the long pedal through the carpet.

I always let the engine idle for a few moments after a cold start before moving off, and then drive gently, even keeping the revs below 2500-3000, until the needle on my temperature gauge indicates the coolant is fully warmed. I believe the engine oil takes longer to warm up than the coolant; before I realized this I would give ’er nails as soon as the temp needle entered the bottom end of the normal range. At this time I also consider the temperature of the gearbox and even the heavy grease in the diff.

Question is, does any of this matter? Should I just be running it hard only a minute or so after start up? Maybe getting the engine up to temperature quickly by loading it more heavily is the best idea.

Sajeev responds:

Oh, yes! BMW really nailed it: too bad all the wannabes (they know who they are) chose Bangle styling and i-drive dysfunctionalism over the intelligent tachometer. But I digress . . .

To answer your first question: does it really matter? With the advent of man-made additives called “Viscosity Index Improvers,” today’s oils are great at minimizing wear at start up. So minimize idle time and hit the road, JG! Unless it’s cold enough to freeze the balls off a polar bear (and you roll sans engine block heater) do not sit and idle! The oil’s additives mean you can quickly drive in a conservative, heat-generating manner.

There is nothing worse than circulating cold oil under no load. The active ingredient to building heat is keeping the engine under load. A mild load, that is. Staying below 3000 rpm is a fair measuring stick for (gasoline powered) passenger cars. You are on the right track: oil takes longer to reach operating temperature than coolant, so don’t go messin’ around just because your temp gauge says it’s cool (so to speak). But don’t sit around lollygagging either.

Piston Slap bonus thought:

Let’s give a round of applause for synthetic oils and high quality oil filters. Synthetic’s viscosity at start up is superior to conventional oils, and has a modest(?) advantage over today’s synthetic blend oils. Most OEM-spec filters have an anti-drainback valve that keeps oil in the filter media and fills the filter body quicker at startup. Never cheap out on oil filters and never accept the off brand junk at many oil change shops. When in doubt, bring your own filter to the shop.