Changes in Manufactures Oil Weight Recommendations

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310
Location
Northern California
Hi all, I was looking at the manual for my wife's 1994 BMW 525i and noting the recommended oil weights. It is interesting to note that 20w-50 is approved for temps of up to 120F, 15w-50 to temps of 100F, and 10w-50 to 80F. As I had posted before, BMW now says that I can run BMW brand, Mobil 1, or Castrol Synthetic in 5w-30 weight year round (in the manual 5w-30 is only approved up to 40F). Given that all Xw-50 weights should be the same thickness at operating temperature, I have to wonder if the reason that the German manufactures recommended such thick oil was due to concerns of high operating temperatures, and the oil burning off and sludging. The temp restriction on wide spread oils with lots of viscosity modifies (i.e. most likely to sludge) seems to indicate this. I have to wonder if the engines are really fine with 5w-30 synthetic and by going to synthetic, the sludging concerns are eliminated. I tend to think this because I remember in the 1980's when it seemed that every Mercedes imported from Germany had serious sludge issues. What does the group think of this long rambling idea? Cary
 

MolaKule

Staff member
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21,950
Location
Iowegia - USA
"I tend to think this because I remember in the 1980's when it seemed that every Mercedes imported from Germany had serious sludge issues." Firstly, I would not use any wide spread viscosity oil unless I knew for sure it had a base composed primarily of esters. The sludge issue of the early eighties was related to the type of Viscosity Index Improver (VII) used at the time. The olefin copolymers were the culprit, since they didn't have the proper VI relationships at the time. It was found that adding PAO's helped the low temp problem and reduced sludge. The problem was almost worldwide.
 
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810
Location
Greece
I have never heard about sludge problems or black death in Greece. On the other heand i am not a mechanic or member of the auto industry. I just now that in car magazines none has mention problems like these. People here use 15W50 ,10W40, 20W50 and 5W40 and lately 5W30 in some VW models. The funny thing is that there is absolutely no trace of 10W30 in the stores and nobody uses it.
 

Cary

Thread starter
Messages
310
Location
Northern California
quote:
Originally posted by Dr. T: NO the recommendations DID NOT change for your car. Only the post `99 models
Actually, according to my dealer and BMW NA they did change the recommendations. Here is an e-mail response to my question concerning oil for my 94 525i: I am with BMW of North America, LLC and your inquiry has been forwarded to me for a response. BMW's approved oils used are: Castrol Synthetic, Mobil 1 Synthetic, and Valvoline High Performance Synthetic with a weight of SAE 5W-30. Please let us know if there is anything else we can help you with. Lauren McLuckie BMW Group Customer Relations
 
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23,591
Dr. T, I will speak only for Germany, because I lived there in the '80s and early '90s, and I still go there every year. In Gemany it's common to follow the car manufacturer's recommendations regarding maintenance. I don't see many "beaters" or poorly maintained vehicles (Cops will pull you over for rust, big dents, tires with not enough tread, loud exhaust, smoke, etc). Also, all cars have to pass a rigorous safety inspection and a smog check every other year. Most people are pretty meticulous with the maintenance of their cars, and while oil change intervals are generally longer there, people do take care of their cars. Now, I'm not speaking for Eastern countries, because I know of the safety issues with their trucks alone, which routinely were (and still are) often not allowed to cross into Germany for serious safety problems.. About the "Black Death" of the '80s: That was due to hotter running engines and mineral oils that couldn't handle the demanding running conditions. Black Death was pretty common with Ford and GM (Opel, Vauxhall) cars, if I remember correctly. I know that my family drove BMW and VW cars back then, and we never had a problem with Black Death. I also remember that synthetic oil became popular at the same time when Black Death was in the news. [Wink]
 
Messages
764
Location
Fairfield County, CT
quote:
Originally posted by Dr. T: And you can get sludge with any oil. Synthetic or otherwise, M-1 or otherwise.
Come on now, Mobil 1 sludging up? [Roll Eyes] There's gotta be some serious mechanical defects (faulty thermostat, gasket, etc) for that to happen. Or massively overextended drain intervals...
 
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2,480
NO the recommendations DID NOT change for your car. Only the post `99 models....and even here after some engine blew up did they switch back to some real oil (but only for these models ie. M engines). The shift back in ~`98-99 was due to the A3 5-30's being introduced. And you can get sludge with any oil. Synthetic or otherwise, M-1 or otherwise. Grade is more important than oil type or brand. The differences in temp. per grade stem from the fact that a 15-50 has more cojones than a 5-50 even though they are both 50 weight oils. Ironically enough, I was thinking about this in the shower the other day [Confused] and all I can come up with is (from what I've read) is that there is a consensus that maintenance is poorer in Euro. than in N.A. (if you can believe it) and they may be even less apt to follow intervals and recommendations than here...(even less in Eastern Europe) maybe resulting in the black death we've heard about. Anyone know anything about the maintenance practises of Euro. car owners in Europe?
 
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