new gtr 37 efi what is the best oil

Most anything with a high zinc formula will work. I've used everything from Farm and Fleet to Amsoil with no oil related failures.

You are about to hear a lot of opinions on this topic. Here is my opinion for what its worth:

Rotella 15-40

The only machines that I have that don't get Rotella are my two strokes, and the wife's car.

x2

3 in 1.

Rotella 10W 30 in my 37 PD....change it every 30-35ish hrs.

Switching over to Valvoline 10w-30 VR1 Racing oil. See how it does. Has a higher zinc content than the mobil one I was running.

It's still a caveman design engine, flat tappets, surface bearing, no need for high dollar shit, Rotella, Rotella, Rotellla, zinc, zinc, zinc, nothing else matters, wouldn't hurt to put lead in the gas.

Kneedeep, that's the stuff I use. No issues with it. Different brand, so the chemistry is different, but it has the zinc, and seems comparable to the amsoil and Rotella. Plus, I can buy it local and don't have to remember to order or store a bunch.

Advance and occasionally walmart up here. Walmart usually only has the 5w, but sometimes they have the 10w 30

One more thing you all need to know. I built many an engine and when Mobil 1 first came out I had just finished a 2 liter 4 cylinder rebuild for my ladies sport car. I used the "New" Mobil 1 on the first start up. After about 500 miles I wasn't happy as that bugger should have been snappier? Changed the oil to the old school Dino stuff and after only about 100 miles the life was there that I expected. My only guess was the Syn didn't let the rings bed in. My conclusion was I run regular oil til it's broken in, then if you want to switch up to more $$ oil then do it. What I did find years ago with my 25HP Kohler long tail when after a change to Syn on the well broken in engine I saw a 75 RPM increase in idle speed just with the oil change.

After a motor is broken in new or after a rebuild and the rings get good and seated oil choice has little effect on them as far as performance goes imo. It's like the old leaded gas was better for the older motors for lubrication, I know a few guys with old model-A's that run a gallon of diesel mixed with their regular gas to help with lubrication. Oil delivery systems have become a lot more advanced so oil choice depends more on use and climate than anything. One of my mechanics used to race lawnmowers and he'd run conventional oil in his mower and change it once a year. It's all preference.