Summer oil

[Yesmar]

Hey guys its been a while, iv been very busy. anyway its getting warmer up here in north east USA, and im getting to the point of needing to change my oil again. i had a heavier almost truck oil running in it this winter. So any ideas on what the best oil/best quality oil is for these bad boys in the summer months. 140,000mile 79 280s

[WGB]

I think all these engines do very well with Castrol GTX 20W50 - the original version and not GTX2 or 3 which have friction modifiers.

Bill

[pez]

I personally run a full synthetic diesel motor oil in my 450se.  Diesel motor oil is just like gas oil, except it has twice the additive package, making it stand up way better.  The other nice thing is that here in the states, it's getting much easier to find diesel motor oil that is synthetic in both summer and winter weights....I live in Colorado and run 5w-40 in the winter and 15w-40 in the summer....Apart from changing my lower oil pan gasket [which took about 30 minutes] when I bought the car, I have not had so much as an ounce of seepage since using syn oil.  It also makes a good difference in fuel economy, esp. during cold starts.

[zedster]

I think all these engines do very well with Castrol GTX 20W50 - the original version and not GTX2 or 3 which have friction modifiers.

Bill

My MBZ mechanic says use Castrol too.

[Yesmar]

Great thankyou guys, this is my first summer with the 116

[DieselCop]

I use Shell Rotella 15w40 in my 300SD with Lucas oil additive.  She loves it!

[carl888]

I use Shell Helix Ultra 5W-30 in everything.  I can only ever recommend a full synthetic and their advantages have been documented for decades.  Even on a 41 degree day the old 300 TD with 605,000 kms on it still has 1.0Bar of oil pressure rising to a full 3.0 bar by 2,000 rpm.  In the two 280 SE's the pressure settles on 1.5 bar at idle under the same conditions.

I do not use this oil for an car that sees any action on the track, I use Helix Ultra Racing 10W-60 this purpose.

Don't confuse oil pressure with engine protection.  If you have high oil pressure at idle, like 3.0 bar for example, all that means is under load as the revs rise the oil pressure becomes so high that it's bypassed and fed straight back into the sump, the oil flow around the engine remains no higher at high rpms and this is when you need it.  Of course there becomes a point where the thinner 30W oil will shear allowing metal on metal but I cannot ever see that happening unless the engine is very very worn.

I would begin with a 5W-40 and go down from there providing your pressure was fine.  As a point of interest, I picked up a 1 mpg mileage improvement when going from a mineral grade 10W-50 oil (That was recommended by the Benz dealer for older cars) to a full synthetic 5W-30 or 40.

Regards,

Carl.