F-Ribs And Sibs - Inflatable Boat Community

Hi guys, just going to do an oil change on my tohatsu 6hp 4 stroke, marine oil or motor oil,? Personally I can’t see why you should need a marine oil as the engine in question is not in contact with any water, and also I’ve used very good quality motor oil in high performance cars and bike, so surely a single cylinder motor will cope with a good quality motor oil?

Well, despite the blurb and I’m sure in reality there’s very little technical benefits, but for peace of mind, I use Quicksilver 10w-30 mineral or Suzuki 10w-40 semi- synthetic marine oils.
In such small quantities the extra costs are negligible anyways.

It’s all down to operating temperatures..
marine oils are blended to work at different running temps...

I only buy the desired marine oil to protect my outboards.

Martin

Marine oils are specially blended to resist effects of long periods at high rpm. Foaming might be one example. Such conditions do not occur in car engines but are common on outboards.

I have a preference for Mobil1 in our cars, but when I called their technical desk they had no product suitable for marine use.

Just like in vehicles, use what the owner's manual says if you want to keep your warranty. After that, feel free to experiment; but for outboards, I'd use an outboard/marine rated oil as indicated.

Agree with others here. Outboard operating conditions, temp and rev range are very different to road vehicle engines, the oil is manufactured to work at it's best for these conditions.
Our Merc E350D is only sitting just below 2,000 rpm at 70mph!! but probably running hotter than my Yam 60 at cruising speed.