Thread: Outboard motor oil question

Uh Oh.... The age old "what oil question"


My Suzuki calls for 10w 40 as well. I order all of my oil from Brown's online out of New Jersey. We don't have any Suzuki dealerships anywhere close to me. Yes, I know I can go and pick up some oil at any car parts store however... although the viscosity is the same, the additives are completely different.

I've read a bunch of forums and a bunch of post that are pro's and con's. In the end I think it is up to the owner of the motor. I've seen some pretty horrible pictures of motors that ran on regular motor oils (specifically the cylinders and pistons) however one can never really know what exactly they were running or how they ran their motor. Yes, each manufacturer says their oil is the best. Although I don't believe that, I do have some belief in the additives that are formulated for certain motors.

In the end, I think it is up to the owner of the motor. For me, I'll do everything I can to ensure I don't have to spend another 12-15 grand for a new one! Even if that means ordering my oil online.
I'm out of Michigan and we get pretty similar weather to Nebraska. I run the 10w 40 Suzuki oil in 30 degree weather and 100 degree weather. Kind of the best of both worlds in my opinion.

Again, I think it is up to the owner but that is what I run

I also am runinng a new 250 Suz. I completely agree with wicklundrh. No more oil than you use, the cost of the new motor, be sure to run 4stroke oil. I personally, run Amsoil outboard 4stroke 10w-30. I believe in the full synthetic.

I run 10/40 Castoroil in my 50 yamaha. Meets same spec as Yamaha oil. Run it in everything I own and never had a oil related problem. Big difference in oils for 2 strokes and all the horror stories that go along with that. Not so much on 4 strokes. Basically an automotive engine running on its end. Main thing is check regular and change regular. Main thing on these engines is proper oil filter. Filter more important than the brand of oil as long as it meets proper spec. Tim, in your case I might look at another out board oil in that weight for their 4 stroke if it is avaliable to you. Not going to be much if any difference in their specs.

Oil related problems normally boil down to 1 of 3 things. Insufficient oil level, contaminated oil(water), or breakdown of the additive package. Any automotive oil in the correct viscosity with an API rating of SJ, SL, SM, or SN will work just fine. Check your oil before startup for level and water contamination. Change your oil at least as often as recommended. I normally 1/2 the recommended interval because like everyone else has said oil is cheap. You can not tell when the additive package in the oil breaks down but changing the oil before its maintenance interval is a good way of assuring it hasn't broken down yet. Dont use aftermarket filters if you can avoid it. Aftermarket may fit and have the same specs but OEM filters are normally higher quality. Last thing you want is a glue seam to split on the paper or the pressure relief spring to break letting unfiltered oil bypass the filter.

Originally Posted by cray

I run 10/40 Castoroil in my 50 yamaha. Meets same spec as Yamaha oil. Run it in everything I own and never had a oil related problem. Big difference in oils for 2 strokes and all the horror stories that go along with that. Not so much on 4 strokes. Basically an automotive engine running on its end. Main thing is check regular and change regular. Main thing on these engines is proper oil filter. Filter more important than the brand of oil as long as it meets proper spec. Tim, in your case I might look at another out board oil in that weight for their 4 stroke if it is avaliable to you. Not going to be much if any difference in their specs.

Thats what I use in my Yamaha 90 Four Stroke ( 10W40 Castrol) and it was recommended to me by the Yamaha dealer that sold me my boat and motor new. Filters...I use NAPA Gold....they are a high quality filter made by WIX.

Originally Posted by Sovran

Oil related problems normally boil down to 1 of 3 things. Insufficient oil level, contaminated oil(water), or breakdown of the additive package. Any automotive oil in the correct viscosity with an API rating of SJ, SL, SM, or SN will work just fine. Check your oil before startup for level and water contamination. Change your oil at least as often as recommended. I normally 1/2 the recommended interval because like everyone else has said oil is cheap. You can not tell when the additive package in the oil breaks down but changing the oil before its maintenance interval is a good way of assuring it hasn't broken down yet. Dont use aftermarket filters if you can avoid it. Aftermarket may fit and have the same specs but OEM filters are normally higher quality. Last thing you want is a glue seam to split on the paper or the pressure relief spring to break letting unfiltered oil bypass the filter.

The biggest point in all of this is what he said in relation to the API rating......
The biggest issue in regards to going with another manufacturer brand is that most of them don't run on the 10w 40 platform (at least not that we see from the dealers around my neck of the woods).
I like Amsoil, and would run it if I could find it around here.

Like I said, I ordered my stuff from Brown's online and have been happy with their shipping and their promptness. I did an oil change last night as a matter of fact!

This AMSOIL 10W-40 Synthetic Formula 4-Stroke Marine Oil