No dipstick on 1989 era 3.0L?

[Scott Danforth]

Rotella T4 15w-40 diesel

 

[Pmt133]

Yeah, try the diesel oil. I've always had issues with rotella and delvac shearing way out of grade in boats but I seem to be an exception to that.

 

[Chris1956]

If the QS 25W-40 is NA, you can use SAE 30 detergent motor oil, for moderate climates. You also might look at the OEM recommendations, as there are a lot of FC-W motor oils (used in 4 cycle outboard motors) in my local Wallyworld that might be recommended.

I never thought "Trying an oil", vs using the recommended stuff, was prudent

 

[ROY WILLIAMS]

What is an oil I can get locally that I can use? Walmart used to carry QS 25W40 but no more. They still carry the Penzoil 25W40 but I’m not sure about that stuff and it’s expensive. The old Merc manual says 40W which I can get at Tractor supply. It should always be above 50*. It also says no multi weights which the QS is supposed to be 25w and 40w oils mixed/ blended into the 25w40.

oil 30w. 1989 engine oil. WALMART!

 

[Scott06]

What is an oil I can get locally that I can use? Walmart used to carry QS 25W40 but no more. They still carry the Penzoil 25W40 but I’m not sure about that stuff and it’s expensive. The old Merc manual says 40W which I can get at Tractor supply. It should always be above 50*. It also says no multi weights which the QS is supposed to be 25w and 40w oils mixed/ blended into the 25w40.

Rotella T4 15w 40, I also used to run super tech 20w50 no issue in my 3.0. Don’t over think it too much.

 

[matt167]

I grabbed 15W40 Rotella T4. My local Walmart got rid of all the marine section in automative. Sporting goods section has the Penzoil and Startron gear lube.

 

[Chris1956]

So the old Merc manual says no multi vis oil, and you plan to use 15W40 multivis oil? It may even protect your motor, who knows?

Gee, how about you visit a MerCruiser dealer or order the correct stuff from Amazon or someplace

 

[Scott Danforth]

Gee, how about you visit a MerCruiser dealer or order the correct stuff from Amazon or someplace

Why overthink it?

The 3.0 has had SAE 30 weight, 10W-30, 10W-40, and 20w-50 recommended in publications from Mercruiser, Volvo Penta, and OMC, and the motor has not changed a bit since 1991, with only slight changes from the mid 70' to 1990 ant the 2.5 liter that it was derived from had less changes from 1962-1990