We have a 1996 850 Turbo with an IPD ECU upgrade with about 200,000 miles. We change oil always at about 3,300 miles.
Our new mechanic urged to change from dino oil (Pennzoil 10W-30) to synthetic.
We have changed the rear main seal already once at 100,000 miles because of leaking and I am reluctant to change oil type in case the engine starts leaking again.
What do you guys think? Should I switch to synthetic or just use the regular oil? If I switch, what weight should I use with the ECU upgrade? Is 10W-30 too thin? Thanks!