Rotella T4 or T5 or T6?? Inquiring minds need to know

[Wilky]

95 Nautique with 1600 hrs on the 290 PCM carb engine.
been using T4 forever no problems. Changes every 50

can’t find T4 this year. Will T5 or 6 do? I know it’s a jump to synthetic, but I also understand that the Zinc content is high in T4 and don’t want to go away from that feature.

‘what say you NautiqueJeff ? Others?

‘’thanks.

[SilentSeven]

www.bobistheoilguy.com

Ask there...internet central for oil geeks. They'll know right away what are the best T4 substitutes....

[Jonny Quest]

Shell Rotella T6 contains high levels of ZDDP and 1,200 ppm of zinc (per the Shell website). T6 is an outstanding oil. Use it and don't look back.

JQ

[bturner]

I'm sure this will get the "oil zealots" going but here we go.....

I've been using T6 in my boat since I bought it 4 years ago, no issues. Been also running Mobile 1 in my 2000 John Deere lawn tractor after the break in period which would be about 2001, no issues whatsoever. Used it in every car I've owned since 2002 as well, no issues. Point being, IMO the whole "what is the best oil thing" is really over done. While I do my best to adhere to the weight recommendations and maintenance schedule of the manufacture, the reality is that if you're using high quality oil/filter and doing your oil changes per the maintenance schedule, it's highly unlikely you're going to have a catastrophic failure due to the type of engine oil that you used. I'll even go further and say (while knocking on wood) I've yet to have an engine failure on any car, boat or 4 cycle engine I've owned and I've owned quite a few older cars and boats. Heck, the lawn tractor is 22 years old now. What's my secret? Use high quality oil/filters, do your maintenance per the manufacture's schedule or at the end of the season, whichever comes first and lastly , don't do stupid stuff to your engines.

We can bench race oil/filters all day but I have yet to have anyone show me a failed engine due to using Mobile 1 or any other full synthetic oil in their car, boat, lawn tractor or any other combustion engine. What I have heard a lot of recently is negative experiences of using rec gas or the pre mix fuels from the big box stores. Apparently, rec fuels while having no alcohol have other additives that are causing issues and the pre mix fuels, which seem to be a great idea, are just garbage.

All this said there are going to be cases where one oil doesn't do it all and that's with engines that were designed for leaded fuels and high zinc content. Been using Lucas Hot Rod & Classic Car oil for the 351 Cleveland in the 70 Mach 1.

But hey, what does my experiences and track record have to do with "what is the best oil" anyway? Probably nothing, but I'm sure the internet experts will know the real answers.....

[northernoak]

I'm absolutely no expert and this was my first year with a direct drive boat. When I was researching which oil to use there were many recommendations thrown around but the oil that seemed to be discussed the most for a 90's to early 00's PCM GT40 was Valvoline VR1 SAE 40. Thats what I ended up going with when I did my oil change this fall. Is it the best? No clue, but it does match the recommendation from the manual. I could buy 4QT locally for the same price as a 6QT case from Amazon so I ordered it even though its more than I needed.

[Scooter G]

I'll have to agree with bturner, run a good synthetic, change often, run a non-synthetic, change it more often. I am probably over kill on changes with the toys & vehicles (and lawn tractor), but gives me peace of mind, and something to do, lol. What I get more wrapped up in is the weight/viscosity of the oil at ambient temperature changes, following manufacture recommendations. Instead of having 8 different weights of oil on hand, I wish I could buy a 5 gallon jug of one oil and dump it in everything. Probably could get away with that, but I want to stay with the zero failure track record (also knocking on wood).

I'm throwing a dollar in the jar that says this thread goes 3 pages...

[bturner]

I don't think you're going to have a problem using the recommended oil from the 95 manual however a lot has changed since 95. If it were me I'd buy the 15-40 T6 and call it a day. That's what they went to later for all the 350 Chevy based engines and the Fords are not different from an oil requirement perspective.