Another Oil thread...

[Adrianl]

But, I PROMISE IT'S NOT LIKE ALL THE OTHERS!

I have a question about my e34 with the big six. She's a german import and a '90.

I get a brilliant deal on shell aero oil through the airport (I'm a pilot), the only problem is that the grade i can get is 15w50. I know this is thick, and would be less than ideal in the winter, but that's okay, she doesn't get driven in the winter. What would people think about flushing the engine and running this in her next summer. It's a synthetic mineral blend.

[BoldUlysses]

I would worry less about the thickness than about the composition of the oil. A quick Google search turned up this info:

http://www.rotaryforum.com/forum/showthread.php?t=15862

Sounds like the big difference has to do with the additives.

[Adrianl]

I've done some research into the actual additive side to the specific type of av-oil that I'd get. It's designed to work in both water cooled and air cooled aviation engines. As well as ones running on avgas (leaded) and mogas (pump gas), and it is ashless. It's been running in my M70'd car for years and i've never had a problem with it. My question is more about the weight for the M30.

To add, when this oil comes out of any of the piston aircraft that I see, it's still clean. The breakdown is almost non-existant it seems (I know it actually does, but i'm just trying to say how good this stuff is in terms of break-down).

[PorscheH6]

Try bobistheoilguy.com unless you want a bunch of 20-year old knowitalls telling you what to do with your precious German automobile.

[BoldUlysses]

My question is more about the weight for the M30.

I ran 15W-50 Mobil 1 in my old E24's M30 for as long as I owned it; no problems whatsoever. Car had 253K and didn't burn or leak a drop.


To add, when this oil comes out of any of the piston aircraft that I see, it's still clean. The breakdown is almost non-existant it seems (I know it actually does, but i'm just trying to say how good this stuff is in terms of break-down).

The environment probably has a lot to do with it—in my experience aviation maintenance tends to be cleaner in general just because, well, it's cleaner up there than it is down here on the ground, and because of the strict maintenance schedules most planes are on. I think it's debatable how much of that has to do with the oil itself.

[93FIM5]

Weight wise it should be fine during the summer, winter well you already know that.

[mottati]

based on the owners manual, 15w40 or 15w50 should be fine for most temps above freezing.

I'd be more worried about what makes it different from normal motor oil. I know my bmw diesel calls for ashless oil, but not because it's necessarily better, but because it'll clog the dpf

[K Fox]

To be honest OP - most here with M30's tend to say that the engine likes thicker oil, as in 15w50 or so. So yeah, you should be OK with it. I also recommend BitOG for some light reading - can be an interesting way to spend several hours (weeks) absorbing info. ;)


To add, when this oil comes out of any of the piston aircraft that I see, it's still clean. The breakdown is almost non-existant it seems (I know it actually does, but i'm just trying to say how good this stuff is in terms of break-down).

One thing about this - everything in aviation I've ever seen is very rigidly controlled as to its use/change frequency. It's either by hours of use or changed every XXX timeframe, whichever is less. And seeing that in aviation failure is very bad, it seems that wear items err on the side of safe, meaning less used than could be. So if your oil is coming out less than new-ish, you'd know there was some other problem that needed addressing, before it caused an inflight failure. That's my experience, anyway, and cars are nowhere near that level of usage. Car oil is always pushed much further into it's life than I'd expect to see aviation oil used. I still think you're fine with that oil - just keep an eye on it, and maybe consider getting oil analysis done a few times, just so you know for sure.

Fox

P.S. Since I haven't read that other link above, I'll ask one question that concerns me - what are the zinc additive levels in that aero oil? I'm now remembering that turbine engines have a slightly different use profile that piston engines, and our cars need ZDDP. I don't know the stardard additives of aero oils like you mention, and I don't have time right now to find out. Just know that zinc saves bearings and cams, so make sure your aero oil has enough zinc type additives, or your engine won't like you.

[nonturbodan]

20w50 is good down to about 15 degrees per the owners manual. 15w50 is probably good down to about zero.

I don't know if aircraft engines are required to use catalytic converters. If not I would expect very high levels of ZDDP. Thats the only reason they have been reducing the levels in automotive engine oil. ZDDP is hard on cats if you're burning a lot of oil.

[Ley3198]

I don't think Mr. Scottessex could have put it any better.


So I guess there is NO BEST OIL, depends on the engine, its application, and other factors, so when you find something that works....stick with it.


Try bobistheoilguy.com unless you want a bunch of 20-year old knowitalls telling you what to do with your precious German automobile.

Great website btw!

Other factors:
1. What kind of vehicle you have
2. What your owner's manual says -- not just viscosity, but certifications (look for acronyms like API SM, ILSAC GF-4, etc.) and change intervals as well
3. Where you live
4. How you drive (easy? hard? fast? slow?)
5. What your daily drive is like (short trips? long trips? city? highway?)
6. Whether your car has any known problems