Pontoon Boat & Deck Boat Forum

My Mercury 150 4 stroke engine is coming up on 100 hours for oil change. My question is can I use Rotella 10w-30 or does it have to be Mercury/Quicksilver oil type? Does it have to be marine grade? The reason I said Rotella is that a buddy of mine owns a diesel repair place and would just give me the oil. Its a synthetic blend. Cold weather is not much of an issue where I live, more summer time heat. Nearest Mercury dealer is about an hour away, and I don't like paying for shipping online.

Not sure, about the rotella, but my Merc 115 is very specific about drinking only 25W40. The hack mechanic at the marina runs 5W30 in all the rental pontoons, and they don't seem to be blowing up the motors, so I don't know if it's a BIG deal.

Based on the owners manual it requires a marine grade oil (FC-W) and for warranty reasons I wouldn't skimp on that. Plus on what I'm reading is this oil is for diesel engines!!
Reiner

My dealer recommends the 25w40 also. While in warranty I buy and use what he recommends/sells and keep the receipt. Not that much to insure no questions if there is a problem.

The owner manual lists 10-30 or 25-40.
The Walmart by me has the Mercury oil in stock I don't know if all Walmart's carry it or just because we are near a lake.
I would use the Mercury oil your only changing it once a year and if you have engine problems you can at least say you used used their oil. The manual even lists as a option the 25-40 semi- synthetic that is used in the Verado its what I use, probably overkill but I like the semi-synthetics.

I would use what Mercury requests, during the warranty period. It is a valuable feature and they can be a-holes.

Now once you get out of warranty, I have been using the Rotella T5 semi synthetic for the last 5 yrs. I think it it a great oil. People shake their head when they see me pour it my Mercury OB.

garygve wrote:The owner manual lists 10-30 or 25-40.
The Walmart by me has the Mercury oil in stock

Warning! Mercury ("QuickSilver") has TWO DIFFERENT WEIGHTS labeled as "4-Stroke" oil! The one labeled for INBOARDS (go figure) is the 25W40. The other one is something like 5W30.

My dealer actually sells Sierra brand semi- synthetic. That's what he recommended in 25w40
http://www.overtons.com/modperl/product ... aQodgUcAXw

The second number is the one you need to pay attention to, the First number really doesn't mean/do anything for an engine that isn't run below freezing. I'm also a firm believer in heavier weight oils if the manufacture allows it, in your case 40 weight, as it provides more "cushion" to absorb all the violence that occurs inside an internal combustion engine. I'd use the factory stuff for warranty and Rotella after. Diesel engine oil usually has more additives that are beneficial to the types of valve train used on outboards.

Thanks for all of the help guys. I think the point about the warranty is a valid one indeed. I am going with the 25w-40.

Many of the ultra high hour Florida fishing fleets use Rotella diesel oil in their Yamaha F series motors. The reason they use Rotella oil is simple--low cost. The thing is that you cannot use it in any motor that has a catalytic converter--which Yamaha and Mercury outboards do not use.

I would not use it in the SHO motors, however.

You can read about marine lubrication on BobIsTheOilGuy.com--the ultimate expert website.

I switched over to Mobil 1 EP on my second oil change--a superior oil than plain Mobil 1 synthetic oil.