Oil question

[orion208]

Since I am fairly new to boating can someone more knowelgeable explain to me why you would use 20w40 oil in an engine that is basically a car engine a volvo penta 4.3 which I understand to be a chevy block engine and for the car the same motor uses 5w30 is it due to the higher rpms.Just curious thanks.

 

[crazy charlie]

Re: Oil question

Most marine engines including yours call for an sae30 oil.Many people use multigrade oils but the manufacturer call for straight weight oil in a marine engine because they run at higher rpms not having a transmission as a car does and it is the high rpms that can break down an oil and ultimately not give the protection needed.There are many boaters on this forum that swear by synthetic mobil 1 and many that use multigrade,but I would rather go with the manufacturers recommendation.as a matter of fact I use a straight sae40 when the summer months get hot for a little extra protection. Charlie

 

[MFG197]

Re: Oil question

Star, it's true they are car blocks, but they are totally different applications. Imagine driving your car in second gear up hill all the time and that 5w30 would break down faster than a conventional straight weight. i use sae 40 in my merc.

 

[JB]

Re: Oil question

Moving to I/O