so what oil should i be using? the merc manual suggests straight weight but if straight weight isn't available the 20W-40 would work. but it doesn't specify which straight weight? 40 SAE? 1986 sundancer 250 merc 260 I/O
You can find straight weights, just need to look.
I find it on line and can have it delivered for the same as going to get it. Use straight 40W in 454, and 50W in cruiser. Starting to use Brad Penn 50W from Speed Way and the cost is great.
Prior, found 40W at NAPA, WalMart and others.
My thought is multi weight is great for engines which need to be fired up when its cold. Straight weights are best and I don't fire a boat up if I have to put a coat on
I like to add a zink additive to my rotellia 15 40 in my flat tappet camed engine. Most all oil has very low zink these days witch isn't good for our older flat tappet camped engines. Just my thing.
i agree about not needing the multi-viscosity in a summertime toy but the concensus here was for the 15w-40 so...
also, my manual says 5.5 quarts and they only had gallons and then 1 single quart so i was still a quart short and was having trouble finding another quart of straight 40 locally so it was easier to get the 15w-40. and my local auto zone has the same shell rotella there.
on another note, had trouble finding replacement belts locally so ordered them here on iboats. should be here thursday. taking it saturday morning to get a new camper top made for it.
I like to add a zink additive to my rotellia 15 40 in my flat tappet camed engine. Most all oil has very low zink these days witch isn't good for our older flat tappet camped engines. Just my thing.
Quicksilver 25w-40 synthetic blend for me. Seems to be in much better condition at the end of the season in comparison to the old QS 25w-40 mineral.
Also seems to have a better and more prolonged oil pressure at lower revs.
