I have a 540 block w TBS blower, dyno'd close to 900hp and been using Kendal GT1 50 weight motor oil. A few have suggested going to synthetic and AMSOIL 20W 50.

Thoughts?

I use Amsoil 15w 40 Marine/Diesel oil. I have a NA 489 and it works fine. I am a Amsoil Dealer I can get you my sponser number and you can buy it online at Dealer cost. Only catch is there is a 6 month trial membership of $20. You can call the Amsoil Tech line and they can advise the type of oil you should be using.

We run it and now have over 230 hrs on our Starboard 565CI running 14 lbs of boost.


Lost oil pump belt zero oil pressure at 170 hrs on Port @ over 6000 rpms for over a mile..

Cut filter open found no metal, changed the oil and on the following day threw a rod at 6400 rpms.

With regular oil we would have exploded on the spot in my opinion.
Were sold on the stuff!

What weight do you use?

I use nothing but Amsoil in everything. In the boat, I'm running the 20W50 race oil.

We run series 2000 20-50

Run the new Dominator 15w-50 Racing Oil. The 20w-50 has been discontinued. I would also recommend the 75/80w-90 Marine Gearlube and the Water Resistant Grease or the Series 2000 Racing Grease.

Dito 15 yrs

thank guys for all your info! I'm planning on switching based on all your comments! Can't wait for summer!

any drawbacks to going with the 15w-50? the local amsoil dealer confirmed they no longer carry the 20w-50