kday

This is totally unscientific. But I just switched to M1 15W50 from M1 10W30 this morning, and my oil temps seem higher. It was kind of hot today (75F -- you hear that, repeater? so it could just be that. But it would make sense if the thicker oil was not flowing as fast that it would not transfer as much heat.

Just curious if anyone else has noticed this.

I had a shop do the change and they only had 0W40 and 15W50 (it's a Porsche/Audi place). I was leaning toward the 0W40 but I have two track days next week. I've never ran anything but M1 10W30, so "MMMV"...

silbergti

You cannot use synth's in dino oil cars line. I had a '85 VW GTI that I bought used back in '87 with about 45,000 miles on her. Promptly switched to synthetic (Mobil 1) and had no leaks. It used no oil between oil changes up until the car had around 200,000 miles on the odometer. At 280,000 miles she was using 1 to 1.5 quarts between oil changes, then I did a motor swap.

If you had a high mileage motor and it used dino oil exclusively, the varnish/gum build up could potentially be "plugging" leaks. Then switching to synthetic which could clean out some of the varnish/gum deposits and now that the "plug" is removed the seal would leak.

Synthetics don't break down like the dino oils do and so you can run them longer. I used a 6,000 mile mark for oil changes on my GTI.

mtg

Can't buy it. Every used car I have purchased for the last 30 years has been switched to synthetics immediately after I bought them. Never had a problem, including a then 7 year old 1976 911S which I owned for 5 more years.

Mark near Chicago

silbergti

as in why some motors leak when you switch to from dino to synthetic and the longer oil change interval.

As an added bonus with the longer oil change interval you are producing less used motor oil.

I guess we will agree to disagree. ;-)

Turbo_Anarchy

Just choose the right viscosity, that would be the issue with clearances.

tpierce

there is info on synthetic oils in there. They state that although not required, synthetics are fine to use in the motors.

tpierce

i used to run mobil 1 15w50 and found that my oil temps on the highway would always creep up when running the car hard or on long trips. Plus it seemed to have a hard time starting on cold mornings. I decided to try Amsoil 5w40 (which is a viscosity range recommended by the owner's manual fro year round use), a big difference. Temps on the highway went down, although the oil warms up to temp faster. Cold starting is better as well. Also, oil pressures drop slightly which isn't a problem.

so to sum it up, i found that the thinner oil warmed up faster, but maintained a lower temp. Plus seemed to cool faster if it did get hot, than the thicker oil.

kday

I think I should have gone with the 0W40 (did you mean "thick" in your subject line?) . It's just the "0" that gets me, even though I understand that synthetic 0Wxx oil is not made from 0 weight oil, as it would be if it was mineral oil. Intellectually I think it would probably be a good thing, reducing startup wear significantly, but... it just feels too low for an older engine.

silbergti

First,I'm not really spending double for oil if you really look at it and synthetic oil has been proven (a fact)to be superior in lubrication.

Just using round numbers to illustrate my price point. You pay about $1.50/quart for mineral and need 5 qts plus a good OEM style oil fiter at $ 4. That brings your oil change to $ 11.50, however you change oil every 3k miles, so in 6k miles your total cost is $ 23. I change my oil at 6k, use Mobil 1 from Wal-Mart in a 5 qt jug it is $ 20 and the same oil filter at $ 4, making my oil change $ 24.

My cost is a whopping one dollar more than what you would spend in 6k miles. Which I gladly spend for the superior lubrication of synthetics.

Second, you are taking some opinion and some fact of your mechanic as gospel and preaching it to be the only correct way and dismissing anybody elses experiences.

You state that motors using synthetic are built using tighter tolerances. Yes, but so are most modern engines in comparison to stuff built 10 or 20 years ago. Most modern engines can use synthetic oil. It would do more harm using the wrong viscosity oil for which an engine is designed.

I bet your mechanic is knowledgeable, but like everyone he his also opinionated.

silbergti

OK fine $ 6, from GermanAutoParts for a Mann