Author Topic: New owner + dreaded oil question (Read 5218 times)

arcter · « **on:** November 26, 2009, 02:48:10 PM »

Hey guys, I'm a new owner of a 91 318iS with 200K on the clock that runs and drives great. The car's engine feels like new, doesn't blow anything out of the exhaust pipe, and doesn't leak a drop of oil. But I noticed that I might be going through a bit more oil than I should, and the oil in there now doesn't seem to be thick enough. I was suggested Lubro Moly 5W-40 but was wondering what you guys thought of that. I live in Southern California so the weather is never super cold, and can get very hot during the summer.

Thanks!

P. Kennedy · « **Reply #1 on:** November 26, 2009, 05:40:52 PM »

The difficulty with asking about oil viscosity, is, you ask 100 different people, you get 100 different answers, as the saying goes.

I was in the exact same spot you are a couple years ago, and I spotted a post on this forum from an actual petro-chemist (don't recall his USER ID) but he recommended Shell Rotella T 5W-40 (in the blue jug.) He indicated he used it in his own E30 & that was good enough for me. I've used nothing other than that in my E30 318is. Motor has 164,XXX on it.

I'll probably get hung out to dry for posting the above, but, just my experience. Your mileage may vary.

DesktopDave · « **Reply #2 on:** November 26, 2009, 08:29:31 PM »

Nah, I agree about oil. Everyone has a different opinion. I use Lubro Moly for brake lube & anti-sieze. I prefer Red Line's full PAO synthetics, especially for gearbox & diff oils but they'll all give you sticker shock. I don't think you can go wrong with any of them.

For my 270k 318i I'll use any of the 'full' over the counter synthetics like Mobil1, Castrol Syntec, etc. Takes a while to get used to the synthetics though...they're really thin (the 5w30 is like water) and pungent. They might give you a bit more fuel mileage, but they might also start leaking from unexpected places...

arcter · « **Reply #3 on:** November 26, 2009, 09:30:04 PM »

Thanks for the responses guys. See, that was why I was thinking my car was going through oil a bit too quickly, though: because the oil is too thin. What can I use that'll make oil consumption better?

P. Kennedy · « **Reply #4 on:** November 27, 2009, 02:06:52 AM »

This may or may not be good advice, but, maybe toss in a bottle of Lucas Oil Stabilizer? Worked wonders in my daughter's Civic.

DesktopDave · « **Reply #5 on:** November 27, 2009, 11:58:09 AM »

Unless you have a visible leak (like out of the crank seal or gaskets), there's only three places your car will use oil. Bad rings, bad valve seals, or bad vac leaks. Oil thickness/viscosity has little to do with the amount of oil the car will burn. You can eliminate these as a cause with a compression and leakdown test. Get your mechanic to do it, or buy a gauge & a pressure tester and try it yourself. It'll give you a first-rate idea of how much life your motor has left in it.

You also might want to take off the intake & see if it's really grimy. That could be where your oil is going too. Dino oil makes quite a mess in the intake when there are vacuum leaks.

I'm a big fan of thin synthetic oils...they give you free horsepower AND better fuel mileage. Something pretty much for free, I like that. I also extend my oil change intervals to at least 7500 miles. I've done 10k on a single oil change for many of my cars (with new oil filters every 5k or 6 mos/whichever comes first) and had no ill effects. The oil came out dark but still smelled right. If it was contaminated with gas/water/oil, that'd be different, of course.

Quote from: arcter;82124

Thanks for the responses guys. See, that was why I was thinking my car was going through oil a bit too quickly, though: because the oil is too thin. What can I use that'll make oil consumption better?

318lotis · « **Reply #6 on:** November 27, 2009, 02:20:00 PM »

i ran castro two months ago, found out later it was not a true snthetic, according to autozone, now im running mobile1 5-30 synthetic, with great results.

dwtaylorpdx · « **Reply #7 on:** November 27, 2009, 04:57:39 PM »

I've had the opportunity to sit arund at big race events with chemists and engineers from the big companies, and got a bit of a backyard tutorial from a couple of them.

All Oils contain a component referred to as pure-base by the chemists that blend the oil.

Standard oils have base petroleum oil + a small percent of the pure-base.

As you increase the quality and move into synthetic you increase the pure-base percentage until you get to full synthetic. BUT! the cheaper synthetic oils are like 75 to 85 percent pure-base and diluted with std oil. The premium synthetics are over 90% and have better additive packages added to help keep metal surfaces correctly tempered in your engine. Redline, Royal Purple, Amsoil are examples of these. Mobile 1, Castrol, are examples of commodity synthetics.

Your engine main bearing clearances are usually matched ot the assumed viscosity of the oil the manufacturer put in. For instance I build a Jeep 4 cyl and my engine builder asked me how I was going to use it, and whether I planned on synthetic oil. Based on that he told me to run no lighter than a 15W50 or 20W50 oil. (I spin this engine HARD playing out in the dunes.)

I've noticed in my 318ti that the engine in it seems to really sound better with the 15w50 synthetic, it came with 10W40 standard oil according to the dealer when it was new. But the engine just has less clatter with the Royal Purple than with Mobile 1.

The only issue is that the service interval light in the 95 318 is calibrated for Std Oil, and with the Royal Purple 7500 miles between changes is more realistic than 3000 with 12 dollar a qt oil...

Anyway hope this helps..

Dave

arcter · « **Reply #8 on:** November 28, 2009, 06:46:51 PM »

What's strange is I had a PPI done by a German car shop where I live and they said the engine was in such excellent condition that they wouldn't rule out the possibility that it wasn't the original. They said this to me several times. Maybe I'll ask them what they think...

dwtaylorpdx · « **Reply #9 on:** November 29, 2009, 01:28:58 AM »

Change your oil regularly = good condition engine. It really is about that simple...

Even a rodded and thrashed on engine can look good if its taken care of...

Dave

DesktopDave · « **Reply #10 on:** November 29, 2009, 09:15:51 AM »

You're right about oil. It's a small investment for long-term payoff. I still have the original engine at 271K. No overhauls, though it needs new gaskets all 'round. BMW builds their engines to last, no doubt about it.

dwtaylorpdx is right about the base stocks. Over the counter synthetics like Mobile1, Castrol, etc. cannot be sold in Europe as synthetics because of their blending. They're a good compromise though.

True synthetics are all labeled as API Group IV PAO lubricants. You'll also be able to tell by the price tag. If you want the best, that's the ticket. Same oil they use in commercial jets & M1 tanks. So slick you can't use it to break engines in.

arcter · « **Reply #11 on:** November 29, 2009, 02:26:47 PM »

Okay, so I had my friend drive the car in front of me after a cold startup. I noticed some smoke which I think was blue only for about a minute after the cold start. There wasn't a ton but it wasn't a tiny amount either. After the car warmed up a bit I see no smoke at all under any conditions. Any idea what my problem may be + how much it'll cost?

I've read it could be valve guide seals, but maybe I can postpone doing them for a while and instead just try a thicker oil one of you could recommend.

dwtaylorpdx · « **Reply #12 on:** November 29, 2009, 03:20:34 PM »

Valve guide seals or something is messed up in the crank case ventilation system.

There are a lot of engines that just blow a little smoke on start and its no big deal.

I had a brand new Toyota pickup in 85 that popped a 5 second smoke show each time it was started cold. It ran 250K miles and used exactly 1 quart of oil between changes its entire life. Also got mid 20's for mileage.

I'd worry about other stuff unless you've got a oil consumption problem.

Dave

arcter · « **Reply #13 on:** November 29, 2009, 03:43:05 PM »

Well the reason I looked for the smoke was because I seem to be noticing somewhat excessive oil consumption. The blue smoke I described lasted until I got out of my neighborhood (when he was on the gas). So about 30 seconds maybe... the car had been last run yesterday afternoon.

91318isguy · « **Reply #14 on:** November 30, 2009, 12:45:25 PM »

I started out with Castrol high milage and then asked my mechanic about using synthetics on an engine over 100k on it. He mentioned to me that the higher milage oils really don't do any good because if you've got a problem with a leak or piston ring it'll still be there even with the high mile oils. Synthetics he said were great if you start a new or rebuilt engine on it. It actually doesn't do good enough in high milage engines to warrant the amount of money spent on synthetic oils. I've run 10w30 Castrol GTX since day one @ 175k and haven't had any smoking. My buddy has only about 90k on his (bought it @ 75k) and uses synthetics and has smoke... who'da thunk. just tossin' my cents.