16v oil question - PeachParts Mercedes-Benz Forum

Joreto · #1 05-27-2002, 10:12 AM

I'm currently using Castrol RS 0w-40 (synthethic)motor oil for my 16v. I've talked to two technicians and both say that this oil is to thin for my motor because it has been driven 190 000 km and that I should use a thicker oil (10w-40 or 15w-40). They also say that if I continue to use such a thin oil I could damage the bearings, cause of the bigger clearance compared to a new motor. Is this true ? Also I think to switch to Mobil 1, is it a good idea ?

Ali Al-Chalabi · #2 05-27-2002, 10:40 AM

Damage would occur to the engine if the oil pressure is too low. If it is not, then follow the recommendations in your owner's manual. There is a chart in there that shows what viscocity of oil to use according to what the ambient air temperatures are. What kind of climate is the car exposed to?

Joreto · #3 05-27-2002, 11:12 AM

Well I'm in east Europe, we have 4 seasons and the tempratures are between -12 C and 36-38 C. As to the owners manual, I don't have one so if anyone could look up the graph for me I'd be very thankful.

Ali Al-Chalabi · #4 05-27-2002, 12:15 PM

I would stick with the 0w-40 in the winter months and use a thicker oil in the summer. If summertime temps regularly reach above 30C, you may want to use a thicker oil during that time.

Although, a a 10-40 or 15-40 will not be significantly thicker at high temps, they are all still pretty much a 40 weight oil when they get hot. And the Mercedes lubrication table I looked at lists any -40 weight oil as approved for use in high temps. Do you know how the oil pressure on the engine is behaving, that is the true test on what oil you should use.

Joreto · #5 05-27-2002, 04:19 PM

The oil pressure allways stays at 3 which I learned is normal for the 16v models.

Ali Al-Chalabi · #6 05-27-2002, 05:08 PM

That sounds like good oil pressure. The weight of oil you are using should be fine, then. If the bearing clearances were too big, then this would be reflected with low oil pressure due to more oil leaking through the larger clearances. A higher viscosity oil will have more resistance to flow, and thus a higher pressure due to less of it leaking through the bearings due to the fact that it is thicker. It is up to you what you want to use, either weight oil is approved, and your oil pressure is normal.

JimSmith · #7 05-27-2002, 06:12 PM

Joreto,

You should have an oil temperature guage too. If the oil temperature and the pressure are within the normal range, which means temperature below 120 C, and pressure pegged at 3 bar, you are fine. One of the adverse effects of a higher viscosity oil is lower flow. Lower flow will increase tempertures of the bearing materials, and the added resistance will increase the temperature of the oil.

So, it is really better for your bearings and the rest to have the lowest viscosity oil that will meet your car's oil pressure and temperature operating norms. I have used Mobil 1 15W-50 for years, but now I use 0W-40 Mobil 1 in my 1986 190E 2.3-16 with 206,000 miles. In any case the engine is like new on the inside. I just had the head off to have it rebuilt and the cylinders were like new.

The local temperatures here range from minus 10 C to around 35 to 38 C in the worst days of summer. I use the stuff year round, and have no problems with oil temperature or pressure. Jim