Oil...seems like a silly topic....

[jwmc1]

But let's hear what your pick for the best oil is for our NA cars

[mytrplseven]

I'm an old school guy and with old cars like these that are used to "dyno" oil, sticking with Castrol GT is always my choice over the synthetic oils. I've heard many complaints about oil leaks after changing over and I don't need to create any more issues than those that come along naturally. But, then again, that's simply my opinion. You'll hear many more to follow. That's the cool part about these forums.

[v2rocket_aka944]

about that time again huh.


20W50 dino blood

[/thread]

[333pg333]

Yeah it's only been what, 2 mins?

[mcanan]

As the previous owner used Mobile 1 10/30 in my 944..I've stuck with it. Expensive but excellent. Also use a K&N oil filter..if nothing else it looks good!

[flash968]

the flat tappets of our lifters like ZDDP, which promotes longevity.

leakage is not caused by synthetic oil. it's related to the chemical bonding between the oil and the seals. any change in oil can promote leaks. it's not just going from dino to synthetic. that is merely the most common occurrence, as most people don't go the other way, and when they do, they use a heavier oil, which has a harder time finding exits. this is a very clear example of post hoc ergo propter hoc.

synthetic oil provides better lubrication than dino oil over time, and holds up better to heat. as soon as it begins to get dirty, multi-viscosity dino oil quickly loses its ability to reach the upper numbers. synthetic oil does not do that nearly as fast. i cannot recommend running dino oil, but unless you are planning on changing your oil frequently (which you really have to do with dino oil anyway), or do not plan to subject your car to heat (which flies in the face of the idea of one of these cars), if you are going to run dino oil, i think i would run a single viscosity oil.

[argiopeweb]

Yep, this conversation has been had before. Search and be confused.

I run 20w50 VR1 conventional. ZDDP is my friend, though it's undoubtedly going to eventually end my catalytic converter.

There's very little cost difference between the synthetic and conventional, so I'm eventually going to end up switching to synthetic VR1 for all the reasons flash968 mentioned. The car started out its time with me on 10w40 synthetic (not VR1), and I miss the durability. I didn't have the patience to wait for the leaks to stop, nor the knowledge/time/money to replace all the oil seals at the time, so I went back to dino.

This said, check your manual for what it recommends for your temperature zone. I'm in Florida and tend to run the car hard all year long. MI is likely going to have different temperatures and (therefore) different recommended oil weights. If in doubt, go with the manual.

[sausagehacker]

Run anything in reason, there's nothing magical about these engines that mandate a pope-blessed oil. As long as good pressure is maintained (a function of temperature and oil viscosity), and the oil is actually lubricating, it's doing its job. As others pointed out, the lifters love ZDDP.

An SAE 30 oil is the bare minimum for these motors, though. Localized temperatures/shear and oil gallery geometry are two of the reasons Porsche specced 20W50 (or close to it) for these cars in most conditions.

I posted this in another thread recently, but if you are unsure if an oil will allow safe pressure across a range of temperatures and RPMs, you can calculate it. Here's the scoop:
944 oil pressure equation - Rennlist Discussion Forums

[333pg333]

Originally Posted by mcanan

As the previous owner used Mobile 1 10/30 in my 944..I've stuck with it. Expensive but excellent. Also use a K&N oil filter..if nothing else it looks good!

Jeezus...it must be cold living in the Tundra!!! Don't envy you living in permanent sub freezing conditions that necessitate using such a low visc oil. Hope your house is very well insulated against those Arctic winds. Yeowch!!

[CHICKS]

Brad Penn 20w50, Mahle Filter, change it once a year.

[mcanan]

Appears that I will be switching to 20-50 next change based on what I've seen here. Haven't used 20-50 since the 80's in the 5ltr. Lola. Long time ago. Thanks for the info.

[cockerpunk]

i wish they made a 0w-50 synthetic. but i use either 0w-40 synthetic, or 15w-50 synthetic. synthetic is always going to be better, and the lower viscosity at room temp will always be better. your gonna want either -40 or -50 for warmed up viscosity though.

[ernie9944]

Dino 20W-50 in my Porsches for over 30 years,not one main bearing failures or any issues what so ever after all those year.

[flash968]

if you change dino oil frequently enough, there is no "real" issue. the problem is that the polymers in a multi-viscosity dino oil do not expand when the oil is dirty, so you never get the upper number. on average, on an engine with mileage (60k and up) this means that a 20/50 only gets up to about 20/35 or so after the first few hundred miles. that can hurt if you plan to push things.

also, synthetic oils have a higher heat resistance than dino oils. that is very important if you plan to drive the car hard. all synthetics are not created equal though, so you have to look at the composition and specs to see how high it will go. for example, royal purple breaks down at a fairly low temp, redline is in the middle, and amsoil is higher. others may be even higher. i don't have that data.

no, you may not have a bearing failure with dino oil. it's not like the sky is falling. however, what you will have is more gradual wear than on a synthetic. that means you get the pleasure of rebuilding your engine sooner.

like they say "pay me now or pay me later"

[pfarah]

I've been using Castrol Hi-mileage part synthetic 10w40 in the summer, 10w30 in the winter. It's probably excessive, but I change the oil every spring and fall with a mileage limit of @2k - 2.5k, averaging about 5k miles annually.