Let's see... I've got a 92 SL1 SOHC with 553,000 km on it. Been
putting Castrol Synth in it and a cheap Motomaster oil filter since
the car had 100,000 km on the odometer. I change my oil every 10,000
kms.
Did a compression test about a month ago and got 185-190 PSI in all
cylinders dry and cold. Didn't bother putting any oil in the cylinders
to do further checks, since I was happy with the readings.
Hope this helps!

Alex