Problem with Mobil 1 0/40

[bostogrun]

I have a 97 328i with 157K. I have always used Quaker State or Castrol 5/30 however, I decided to try Mobil 1 0/40 because of extreme cold here in MN. I have never had any issues with oil consumption or leakage. After switching to Mobil 1, I began to see drips on the garage floor. It appeared to be coming from around the oil filter housing, a common failure, so I changed the gasket actually twice because even after carefully changing the gasket and torquing the housing to 16 lb. it still leaked. Oddly enough it didn't leak when the engine was warm only in the morning after a cold start? It would dump a small puddle. I drained the Mobil 1 0/40 and switched back to 5/30.

My guess is that the 0/40 is just too viscous (thin) in the AM and it leaks out between the precise mating surface between the engine block and the filter housing? I also noticed the Mobil 1 was seeping out around the upper O Ring of the filter housing, the great big one.

I just switched back to 5/30 and cleaned the area up and laid under the car and didn't observe a drop leak. Anyone out there had an experience with this?

I hope it doesn't leak anymore with the 5/30. Is 0/40 too thin for an old engine?

Please give me input. It's not leaking from the front main seal

[bostogrun]

I think I found the root of my oil filter housing leak problem. Most sources note a torque spec of 16lb for the 8mm bolts but a writeup on another forum notes that his housing leaked after torquing to 16lb so I upped the torque to 21lb , the max allowable is 24lb for 8mm bolts.

The gasket , actually a kind of O ring, barely protrudes from the housing (less than a mm.) so perhaps it's necessary to apply a little extra torque to assure a tight seal because the bolts may have stretched a little thus requiring more torque. Were talking tight tolerences here.

Perhaps the cold temp contracted the metal surfaces enough to allow seepage of the thin 0w oil that would explain the puddles at start up but no leaks at temp.

This an example of one of those easy jobs that turned out to be a real PITA.

I did get rid of the 0/40 it's just too thin for an old motor. The 5/30 will actually flow at -40 where as the 0/40 will flow at -57 so it's probably not necessary or prudent unless you live in the Yukon Territories

[coolbear1]

my personal experience with Synthetic oil leads me to believe it has a tendency to cause leaks on an older engine. I work in industrial refrigeration and use poly oil as an alternative to mineral oil due to its compatibility with the new non clorine HFC, or ozone safe CFC refrigerant alternatives. The manufacturers will not admit to it. These oils are excellent lubricants, but have a down side in that they are agressive, or solvent like. They may atack some gaskets and o rings, and may scour the engine.

They recomend changing the o rings when retofiting R12 automotive air conditioning system to R-134a not because of the freon, rather because the mineral oil should be also changed to synthetic POE oil.

[bostogrun]

At long last, I believe the problem has been solved. After considerable frustration and 3 redos of the filter gasket job, I observed that the actual source of the leak was a bulging o-ring on the top of the canister. The large o-ring that comes with the oil change kit. It was really hard to see because it was obscured by the vanos line banjo bolt. I pulled the black plastic filter cap and after careful observation, I discovered that there were actually two o-rings on there. I know that sounds weird, but anyone who has examined these caps will see exactly how it can happen. There is groove in the cap right at the end of the threads on the outside of the cap and an o-ring can get trapped there. It looks like there should be two because there is a groove there,

I removed the two o-rings and went to a dealer and bought an oem o-ring and installed it carfully and thank God no start up oil leak. By the way, I read on other posts that there can be problems with Fram aftermarket filters. The o-rings are not the right size and can cause leaks around the top. When I visually observed the two side by side the Fram Ring was not quite as fat as the oem one. The oem one also seemed more rubbery. When installing that ring, you have to make sure it strechted on there correctly that is pulled firmly on to the ridge on the plastic cap if it isn't it can seat improperly.

In my case the extra o-ring interferred with the primary o-rings ability to seal correctly because when compressed under torque it pushes the top one out causing the leak.

[Bigwheel]

I switched to Mobil 1 o/40 around 175k, and shortyl had to replace my oil pan gasket. Ever since then though, I've had no issue with the 0/40. I'm a tick below 260 and still going great. I live in atlanta so it does great with a ton of heat and temps well below freezing. Glad to hear it was nothing catastrophic!