As an ex-mechanic and more than a little anal about my cars. I have done way to much research on what to use in my vehicles. I have become loyal to Amsoil. I use it in everything, I have a 38 year old lawnmower with the original spark plug. I have an 03 Suburban with 360,000 hard miles on it and it still runs better than new. I have over a million miles on my last 4 vehicles. I run it 10,000 miles between changes. I run 2 seasons on my boat and the oil is still clean when I change it and I run it hard and get the oil to 280 degrees and keep it there for miles. Does it cost more that Walmart oil? Yes it does but then it really doesn’t. If you lease or like changing vehicles regularly don’t bother. I spend years getting my vehicle exactly the way I want it. So what if it’s 17 years old.

wow ten k miles on an oil change. I saw the new móbil one oils recommend 20 k on oil. I’ve only gone 5 k on my oil changes 3500 with Castrol Dino oil in my daily driver.
For me the difference in temps the full synthetic can endure is so much higher than Dino oil. And things do occasionally go bad. I always try to watch my gauges but we have pretty much all over heated our stuff for one reason or another.

I researched this back in the day and I think the conclusion was that they started from Dino oil to reach what was essentially the same as synthetic. So I started using the Castrol syntec as it was quite a bit cheaper than Mobil 1 at the time.

But I generally just take whatever they call synthetic at the quick lube place. 10k mile change intervals, got 390k on an olds aurora, 190k on an XJR Jaguar. Granted this is much lighter duty than a boat.

For whatever reason the Suzuki oil is not marked as synthetic that I’ve seen, and it’s egregiously expensive.

https://behrents.com/parts/joe-gibbs...-oil-02606.asp


It`s $8.99 if quantity is more than 20.
Pretty good deal for full synthetic designed for marine.