high performance oil with high amounts of zink make black sludge in the bottom of the pan,it is the zink seperating from the oil.i can tell you that it happens pretty quickly.if you are not running a flat tappet cam you don,t need all that zink.the brad penn oil is full of the zink and leaves the black sludge even if you run 200 deg oil temp.a lot of guys are going with mobil 1 15w50 to get away from the zink sludge,including me.

You will need to look it up, but top of my head says Mobil 15W-50 has more than Rotella,

Although I've never really ran Rotella in a boat I have used 100's of gallons in Diesel trucks. When Shell can out with the T6 formula I started using it exclusively. What I noticed over the years was trucks that notoriously had injector issues (Fords) stopped having injector issues. These were trucks I services for years. I'm so confident in T6 my brand new truck that carries 100,000 mi warranty lost its factory break-in oil and got filled with T6 and a Mobil 1 filter. Oil temp 199*. Often thought about trying it in a boat but haven't. I may give it a shot in my new motor oil change will be 5 gallons and at $20/gallon it won't break the bank.

I use it (Conventional Rotella 15/40) in a bunch in boats, mostly stock ones. A few 502's, Many small blocks. Some date back to mid eighty's.Never been apart. Still running good to this day.

Did use it for Gen V 502 for bunch of years. When it came apart to modify, it was fine inside. But this was about 8-10yrs ago, so was before the formulation change.

Edit in: A small block (bazzilion hrs) was mod'd also, Pan came off to do cam change and etc. Very clean. This too was before the formulation change.

I switched to brad penn in all performance apps, but have been running the rotella in my 454's in my gibson for a couple of season's now, so was hoping that somebody ran into deal with that oil and cold temps ?

I am running Rotella T5. Only been using it 2 seasons so too early to tell. One thing I did notice is I picked up a couple hundred rpm's changing from merc oil to the T5. I dont really know what to make of that but gaining rpm's is better than loosing rpm's

Chris

Its all in the way you get the oil out of the motor. If you suck it out or the pan has a side drain you will slowly build up sludge. Install a sump drain in the pan next time it's off , weld it in on. That way all the oil comes out. Change it when it's hot. And you won't have sludge. Even my diesel fuel tanks build up sludge if not checked and drained every so often. This is the perfect scenario of sh't happens

i will also say that the high zink oil looks fine when drained and if you don,t remove the pan you won,t know the black stuff is in it.

i just looked it up,you are correct,conventional rotella 15w40 is 1200 ppm zinc,mobil 1 15w50 is 1300 ppm.

i wish this was true but i don,t think so.
my pan,s drain from the bottom and still see the black stuff covering the bottom of the pan,i just cleaned&installed one yesterday.