Oil selection

[Pmt133]

Yep the only way to know is to run a virgin oil analysis. I have a 98 Jeep with a flat tappet cam (4.0 six) and it’s been run on Valvoline max life 10/30 for years. And no issues with the cam or lifters at 182,000 miles..this oil has like 750-800 ppm of Zinc..on the Jeep boards they are always recommending this or that oil but much of this is just conjecture. Just do oil analyses, then you’ll know if the oil is good enough!

The problem is way deeper than zinc. It was always a chemistry issue and a parts issue. There are millions of flat tappets out on the road right now running whatever the current blend of oil is for their spec and are all fine. Without starting a pissing match or anything else I'm leaving it at that.

Whatever weight oil the manual reccomends as a substitute is going to be fine.

 

[cyclops222]

If you run at WOT for hours ? Good luck with any oil. I know 2 people who do. Sell their boats every 2 years.

 

[Lou C]

However most inboard engine manufacturers recommend running at 75% of redine or approx 3500 rpm. If you do that, and make sure the boat reaches the specified max RPM & doesn't run hot, use good oil that doesn't break down...you should get at least 2,000 hrs if not a lot more.
Also regardless of what is said, use 89 octane or better, marine engines are under constant stress and one thing you don't want is overheated combustion chambers due to low octane fuel for the load....

 

[Captain Caveman]

04 4.3 gxi

Doing research on oil. Is marine grade full synthetic required?? I've always ran wolfshead in my my mercruisers with great luck this is my newest engine though just checking. I just purchased this boat and cannot read the writing on the oil cap any longer please help.

Find the exact owners manual for your boat. Run the recommended type of oil.

There are a lot of smart people on this forum. However, you are taking a risk when you trust anything that you read from anonymous people on the internet. There is no proof that anyone tested any oil, or that they didn't damage their motors running XXX oil.

Do what you want with your motor and enjoy it but beware of internet advice...