What weight oil to run ?
 

I am running hyd.roller lifters and with heavier weight oil like a 20-40 I got alot of tapping,the manufacturer of the lifter says to run light oil like 5-30 it stopped the tapping. My question is has anyone heard of this? I never have.

I wouldn't run 5w30 in my boat engine if you paid me...What brand??

What lifters are you running?

20W 50 BRAD PENN with a splash of ZDP

20w 50. Conventional vavoline. Change every 12-15 hours. Supercharged 850 sc

What type of oil are you running? 20w40 merc syn or Castrol synthetic??? Why not run a 15w50 it will give youself the protection you need and stop the lifter noise, if you indeed need a lighter oil for what ever lifters you are running.

dozer,

What are the block/head materials??
Iron/Iron
Iron/Aluminum
Al/Al

What is the brand of lifters in question?
What preload are you adjusting to?
What is the seat/open force of your valve springs.
What is the springs rate?

Bob

ZDDP not required with roller lifters, but curious what lifter you are running? That oil weight seems light for a boat motor. I would be more inclined to run a straight 40W first if your temps are in line. Loosing oil pressure is not a good thing, I would look at if your oil is draining back to the pan well. If it is hanging up top to long that is not a good thing. Check your oil drain return holes in the back of the heads for restriction, or you might need to plumb oil return lines to the pan, or get a bigger oil pan for more volume. Sounds like the oil pan is getting sucked dry.

ZDDP is required in a oil as it is a multifunctional additive. It not only is an anti wear, but an anti-antioxidant, it help prevents the oil from thickening over time.

Roller lifters need less zinc than flat tappet lifters.

A 20w40 and a straight 40 are the same viscosity at 210F. The 20w side of the 20w40 will help in cold engine starts, the oil pressure and flow will be faster than a straight 40.

I am running 20w50 in a roller cam motor.

Ken

I run Rotella 15w40...