Cigaretteman

Mobil 1 15W 50

masher44

Mobil 1 V Twin 20-50

CROWN MAN

Mobil 1 20/50

Cat man do

VALVOLINE 20-50 VR1 RACING

drpete3

So why dou you guys run somthing other than a straight 30? Is that what your engine calls for or am I missing somthing? Please educate me.

CigDaze

Merc. 25-40 or Mobil1 15-50

jafo

There was a time that single viscosity index oils were better for marine engines due to the protection they offered once warmed up. Mercruiser also specified at that time an alternative with their 25W-40. The problem was, thick oil at start-up of a cold engine.
Oil formulation has come a VERY long way in the last 10-15 years. Multi-vis oils allow for the oil to flow better at cold OAT/engine temps than single SAE grades, and with the addition of their viscosity index improvers, exceed single viscosity oils' protection on the upper number (a 10W-30 oil will actually protect up to about a 37-38 viscosity index).

drpete3

So is it safe or better for me to run the rotella 20-40 than the straight 30? 1989 454 mag

Biggus

Yes, what's the best protection for my old flat tappet motors without the expense of a full synthetic?
Does the Rotella oils really have enough zinc to provide proper lubrication for the old flat tappet mills?

Is there an additive that includes the zinc needed for the flat tappets that can be added to the oil of your choice?

Kurt

Panther

The valvoline racing oil has higher levels of zinc. I've used it for a number of years and never had any problems.