Mercruiser Engine Oil Weight- SAE40W vs SAE30W

[tc123]

I have a 1987 Mercruiser 470 that I normally run straight SAE 40 oil during the boating season. Anyone have experience using SAE 30 in this motor during the summer months? I'm having a hard time finding SAE 40W. Is SAE 30 too light? I don't want to risk any engine damage because of a different oil. Also, the motor has less than 300 hrs. on it, don't know if that changes anything as far as my question goes.

 

[EddiePetty]

Re: Mercruiser Engine Oil Weight- SAE40W vs SAE30W

...trying to stay away from an oil debate thread!!!

I use only 30w in our 470, especially since we usually boat only in the warmer months.

I have noticed more and more manufactures are recommending straight 30W.

 

[HT32BSX115]

Re: Mercruiser Engine Oil Weight- SAE40W vs SAE30W

There's no debate. Either use what Mercruiser suggests or use whatever you want.....everything has been tried successfully.

Below is what they suggest:


http://www.mercurymarine.com/servic...tenance/faqs/mercruiser/?category=parts#MCOil

But in a "nutshell" If you don't want to read the above, Read the following:

This crankcase oil recommendation supersedes all previously printed crankcase oil recommendations for MerCruiser gasoline engines.

The reason for this change is to include the newer engine oils that are now available in the recommendation. Older Operation, Maintenance & Warranty manuals, Service manuals and other publications that are not regularly updated will not be revised to show this latest engine oil recommendation. Current Operation, Maintenance & Warranty manuals, Service manuals and other service publications that receive regular updates will receive this revised recommendation the next time they are updated.

Regards,


Rick

 

[tc123]

Re: Mercruiser Engine Oil Weight- SAE40W vs SAE30W

OK, thanks for the advice guys. Didn't realize this was such a heavily debated topic. I was able to find Valvoline SAE 40W and I'll stick with that for now.

 

[geneseo1911]

Re: Mercruiser Engine Oil Weight- SAE40W vs SAE30W

I can't find 40W locally, so I'm using 30W. I have an '82 260 (350 chev.), and it carries 30lbs. oil pressure at idle on 90+ degree days.

I can get the Quicksilver 20W-40, but I don't want to pay for it. Besides, the sooner I wear out the 260, the sooner I get to build it into a 383....

 

[fmalott]

Re: Mercruiser Engine Oil Weight- SAE40W vs SAE30W

stamped on my 1983 470 rocker arm cover it says to use SAE 30W