I put in Castrol R 0W40 two month ago(3000km ago) and everything looked pretty good until this week. The temperature in Hong Kong always go up to 32'C plus in this week and I really feel the engine is not very comfortable with this oil. Today after I drove in traffic for a while and when I turned off the engine, even the "STOP, LOW ENGINE OIL PRESSURE" flash for 1/5 a second, I think the oil was really too thin at that time. I have never had this problem when I used Mobil1 5W50 or 15W50 but with 0W40(In fact Castrol RS 0W40 is suggested to use in my 95 BMW 740i in their web site)
0W40 oil may be too thin for my BMW in hot weather
- Thread starter hungdynasty
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The Castrol R 0-40 should be fine. There is nothing wrong with that grade nor the oil compared to the 5-50 or 15-50 that you've used.
Did you recently wash the engine bay? Sometimes washing causes water to get into the oil pressure sensor located right next to the oil filter cannister. Check it's connection anyway. Otherwise, this sensor will not operate when the car is turned off, so something doesn't sound right....
Did you recently wash the engine bay? Sometimes washing causes water to get into the oil pressure sensor located right next to the oil filter cannister. Check it's connection anyway. Otherwise, this sensor will not operate when the car is turned off, so something doesn't sound right....
JHZR2
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I wasnt all that happy with M1 0w-40 in my E30 M42 BMW. Rotella 5w-40 does a lot better, with UOAs to match.
Nver had a pressure problem with either though.
JMH
Nver had a pressure problem with either though.
JMH
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How many miles are on that '95 BMW? There may be an issue with worn crank or rod bearings, which is not exactly an uncommon problem with BMW engines at relatively low mileage (100k miles and up).
I do not believe that a 0W-X oil belongs in any older BMW motor.
I do not believe that a 0W-X oil belongs in any older BMW motor.
I did not like the UOA results in my 95 525i with over 100,000 miles with 0w40 Mobil I. I had high lead. Even so, no known oil light/pressure problems.
I am now using 5w40 Truck and SUV. Will have UOA on that oil in a week or so.
I may go to 15w50 Mobil 1 next spring. Or is it 20w50? not sure.
I am now using 5w40 Truck and SUV. Will have UOA on that oil in a week or so.
I may go to 15w50 Mobil 1 next spring. Or is it 20w50? not sure.
12.9 cst at 100°C. Man that is one thin 40W!! Oddly enough, Castrol USA web-site won't show me anything but 15W-40 and neither does Australia (Oz) web-site.
Dr. T is correct, but I have to wonder if the selection is less than perfect for your car.
Seems like maybe something about that particular model year won't show me a syn unless I plug in lower ambient temp. values. Perhaps it is a bit thin coincidentally?
We don't get Formula R, but I have to plug in a mild ambient number to get the selector to recommend USA Syntec 10W-40 and it is slightly thicker, but not by much.
Dr. T is correct, but I have to wonder if the selection is less than perfect for your car.
Seems like maybe something about that particular model year won't show me a syn unless I plug in lower ambient temp. values. Perhaps it is a bit thin coincidentally?
We don't get Formula R, but I have to plug in a mild ambient number to get the selector to recommend USA Syntec 10W-40 and it is slightly thicker, but not by much.
Dr.T , the BMW warning system work like this, when there is low oil pressure(including at the start), the oil pressure light comes up until it reach the proper pressure(normally within a second). If the light stay on for more than may be 10 second than the "STOP ENGINE LOW OIL PRESSURE" message will come up to tell you to stop the engine and this message will come up again after you turn off the engine.
In my case, the oil pressure warning light and warning message never came up during the engine running so I think the oil pressure was still within limit. However, I guess the oil pressure must be somewhat arround the lower limit which caused the on board computer to get enough warning from the pressure sensor and display the "STOP ENGINE LOW OIL PRESSURE" message when engine off.
haley10 yes I know it's a thin 40 oil. I think the Mobil1 5W50 and 15w50 has a 17.?? cst at 100°C and that why I did not have this kind of problem in the pass. I tried R 0W40 because I trust the Castrol web site and in fact the engine still burn no 0W40 oil as before. It may be that my car is a bit too old to use this oil and I will go back to Mobil1 in my next oil change.
My car has 110000km(68000miles) mostly city driving. But anyway today's temperature drop down to 26, 27'C and my car ran perfectly, engine running smooth and no oil pressure warning. You are right, it seems that 0W40 is not really for old BMW and I will go back to grade 50 oil.
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