5w-50 synthetic or heavier oil in 95 bmw 525i ??

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What does everyone think of 5w-50 synthetic or heavier oil (15w50) in a 95 bmw 525i with thr 6-cylinder m50 tu engine with vanos? I was thing specifically about Pennzoil platium 5w-50. currently using Mobil 1 Truck and suv. I think it is 10w40 and uses no oil between 4,500 mile oil/filter changes. These cars were originally speced for heavy weight conventional oils? I have tried 0w40 Mobil 1 and engine was just louder sounding and had high anounts of lead in oil analysis. Lead lowered with heavier oils. Just looking for opinions.
 
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M1 15W50 is a very good oil. I used it for years. I`ve been using 20W50 and will be using M1 15W50 for my winter fill. I got a jug of it w/the $10 rebate Mobil was offering awhile back.
 
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SynPower 20w-50 is easy to find and quite good. I'd be inclined to try one of the Mobil 1 HM oils.
 
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x3 on the 15W-50 or 20W-50 synths. Between M1,PP and SynPower, I would get the best priced jugs or when on sale stock up. All are very much up to the task of the M50 engine over 150k miles.
 
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It seems your car's bearings really like/need thick oil. While I'm a proud member of the "Mo thickah, Mo bettah." crowd, I do find it odd that something like 0w-40 is so 'thin' as to cause excess bearing (lead) wear. I hope the car isn't sick. Anyway here are some High Temp High Shear numbers for the syn oils I could find. The HTHS viscosity test is designed to model the oil's performance in the bearing. Higher numbers produce a thicker hydrodynamic oil wedge, all other things being equal. PP 5-50 4.1 (Kinda wimpy for a 50) 15-50 5.2 (More like it! Is this available in your area?) M1 0-40 3.7 (Not all that thin, although it does have a reputation for shearing with use.) 10-40HM 4.06 15-50 4.5 5-40 truck 3.9 Redline (You want HTHS, you've come to the right place!) 10-30 3.8 10-40 4.7 15-40 4.7 15-50 5.8 20-50 6.1 Castrol and Valvoline offer no HTHS values (that I could find) for their Syn stuff. IMO, I'd look for something a little thicker than the PP 5-50. If M1 0-40 is causing problems, I'd aim for an HTHS in the high 4.x ~ 5+ range. (Just a wild arsed guess!) The M1 15-50 actually seems a little thin by these standards, but it has lots of additives and should be more stable than the 0w40. Try some Redline 10w40 (perhaps spiked with a qt. or two of xW-50) and post UOA results! 4.5K is a somewhat short oil change interval. Getting 6K should be easy for any of these oils, and will help justify the per-quart expense.
 
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 Originally Posted By: Russell
What does everyone think of 5w-50 synthetic or heavier oil (15w50) in a 95 bmw 525i with thr 6-cylinder m50 tu engine with vanos? I was thing specifically about Pennzoil platium 5w-50. currently using Mobil 1 Truck and suv. I think it is 10w40 and uses no oil between 4,500 mile oil/filter changes. These cars were originally speced for heavy weight conventional oils? I have tried 0w40 Mobil 1 and engine was just louder sounding and had high anounts of lead in oil analysis. Lead lowered with heavier oils. Just looking for opinions.
I'd stay with a 40 weight not from M1. M1 alone will explain the noise (it made my M52 crazy loud). Is it warm where you are? 15W40 dino HDEO year-round will probably do you fine. Or a 5W40 HDEO or Amsoil AFL. You've never tried GC?
 
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Mobil 1 15w50 will work great in your car as it has in my '97 Mercedes (used 15w50 from 100k - 235k). Recently replaced it with Mobil 1 10w40 High Mileage to help with a slow leak. Car runs just as well as it did on the 15w50 and the leak is almost non-existant. Either 15w50 of 10w40 HM should work very well with your car with their high levels of ZDDP.
 
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In his climate, 15w-40 and a UOA would cinch the deal. The problem is that guys who are into their cars and oil always want synth, even if it is not warranted.
 
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Hello and sorry for bumping an old post, but this is what came up in the search results when I had a very similar question, so I thought to continue the discussion. I also have a 1995 525i with M50B25TU engine (385 thousand kms on it) and have been using a Ravenol 0W-40 for the last year or so, but while it appears to work just fine when still fresh and especially at lower ambient temperatures, once the summer kicks in, I start hearing a bit of a tappety noise from the lifter area after the car is warmed up good. I was wondering if switching to a 5W-50 oil will help and I actually picked up some Motul 5W-50 ester-based oil which was on sale. Still have not had the chance to change the oil, but in the meantime, would you say there would be any harm in trying that thicker 5W-50 to possibly help with the noisy lifters vs what I ordinarily run?
 
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Russell

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I currently use Castrol 10w40 high mileage oil with a can of liqui moly oil saver or Mos2, I alternate. I change about once a year. as I only drive about 1,200 miles a year in it now. Less these days. smile
 
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Originally Posted by Russell
I currently use Castrol 10w40 high mileage oil with a can of liqui moly oil saver or Mos2, I alternate. I change about once a year. as I only drive about 1,200 miles a year in it now. Less these days. smile
Wow, you still have the car, really nice! Viscosity at 100C of Castrol 10w40 high mileage is 15.6 cSt, which is a bit more than my current Ravenol's 13.25. I may give that a try for my next oil change, but I'll probably be fine using the 5W-50 Motul I bought for the summer now.
Originally Posted by ka9mnx
Does it need a valve lifter adjustment?
This engine has hydraulic lifters that are supposed to self-regulate. While the engine still works great most of the time, especially in the summer and after driving at a bit lower RPMs (such as in town traffic), I can hear the ticking noise at idle.
 

Russell

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Mine occasionally has a slight tappet noise, but not with fresh oil in it. Lately, all iI take are short trips. Most 2-3 miles and an occasional trip of 50 miles. The following is my BMW in its current condition. [Linked Image]
 
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Had the same car with a 5 speed. I always ran 15w40 Rotella, Delo, Delvac. Sold with 200k miles and engine ran great. Got a 98 328i, wish I kept the 525i. E34's are legendary.
 
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