Cannot find SAE 20 or 20W motor oil for 44-year-old Sea Ray I/O

[Don S]

Re: Cannot find SAE 20 or 20W motor oil for 44-year-old Sea Ray I/O

NOTE: We do not recommend non-detergent oils, multi-viscosity oils (other than as specified), non-FC-W-rated synthetic oils, low-quality oils, or oils that contain solid additives.

Didn't look at the link I posted from Merc in reply #16 did you. That exact quote is there.

 

[fmalott]

Re: Cannot find SAE 20 or 20W motor oil for 44-year-old Sea Ray I/O

i was just quoting from the service manual i just mentioned your name so redgoat could find it i was just trying say no one mentioned what the quote was saying. i already have that link Don S and i was talking to my mechanic and he was explaining what the quote was saying about non-detergent oils and multi-viscosity oils and so on and some replies are saying 10w-30, 10w-40 is ok does this non- detergent oils still matter why are they mentoning this
sorry redgoat i'm not hyjacking i'm trying to get your questioned answer because it will benefit both of us

 

[Silvertip]

Re: Cannot find SAE 20 or 20W motor oil for 44-year-old Sea Ray I/O

Any engine with hydraulic valve lifters absolutely requires a detergent oil. Lifters are manufacturered with very close clearances and varnish build up will cause them to begin to stick and clatter. Chevy for example began using hydraulic lifters in the 1950 model year cars with the automatic transmission. Oil filters were optional back then and it didn't take long for lifters to clatter if the engine didn't have clean oil. Multi-viscosity high detergent oils came along shortly after and the sticky lifter issue went away. The switch from mineral to synthetic oil can cause a lifter issue because the synthetic oil cleans up existing varnish and gunk and can plug up a lifter. The problem may or not clear in a short time. But generally the rule of thumb with making this switch is as follows:

If an engine leaks oil it will likely leak more with synthetic oil.
If an engine burns oil it will likely burn more with synthetic oil. (Unless consumption is due to stuck rings/carbon build up in which case it may actually improve over time).
If an engine uses no oil and has no leaks it will likely continue to use no oil and will not likely leak.