manual I checked said use monograde oil
SAE 30 or 40 in 1GM engine
, so did the Caltex "find oil" web page.
But one maintenance
sheet I saw said multigrade 15W40 and some other references
I can't find now said the same.
Is it okay to use multigrade 15W40 in the 1GM engine
or best to stick with monograde?
I confess I have used multigrade oil
in my 4 stroke
lawn mowers for decades though the manuals
say monograde, and the engines outlasted the other components. I used it as I am totally lazy and cheap
and reasonable quality multigrade was easier and cheaper to buy in bulk than the hard-to-find expensive small bottles of monograde oil that were only stocked in the specialist mower shop.