Rotella for 6.0L Gasser

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I've got a 2000 Silverado with a 6.0L, purchased at 110,000 and currently with 265,000 miles on the clock. I've been experimenting with different Rotella viscosities as they also work in my motorcycle that needs a JASO MA rating ('89 KLR 650). I do some stop and go driving and will start commuting approximately 1:15 hrs for work. The owner's manual recommends 5W-30 for all temps and 10W-30 for above freezing. I live in Maine and the amount of time when morning temps are at or above freezing only lasts a few months.

This engine has the infamous 6.0L "knock" on cold startups. It's done this since I got the truck at 110,000 miles. I base oil changes and suitability of oils for this engine on the amount of knock on startup. Rotella T, T5, and T6 have excelled in this category; Mobil 1 syn, NAPA brand, and Castrol GTX have not. Rotella T are the only oils that haven't had reduced OP towards the end of an oil change interval.

I'm currently running T6 5w-40. It held up great over the winter with startups commonly around 0F, and occasionally into negative teens and twenties. I'd like to keep running the T6 in both of my machines. The issue is when warmed up my oil pressure runs at minimum 40 PSI, and when on the highway (2000-2300 RPM) OP is between 55-60 PSI. I'm assuming there is a high pressure shut off that keeps pressures below 60, as I've never seen it above that mark. Is the 5W-40 too thick? What are some recommendations for other HDEO's?

Thanks, Joe
 
That's fine. I've had high mileage engines with 7psi at idle hot and 40 psi on the highway hot that ran another 100K. Your pump may be "relieveing" at 60 psi... But that waht it's supposed to do.

Don't sweat it. And a 40 hot is still way thinner than a 5W at cold start. No issue unless the motor rattles ...
 
Mobil1 0W40 is a very robust oil with a high TBN. The newer version that says FS on the bottle has a GTL oil base. It is available today and cheap in 5 QT jugs at any Wal-Mart.
 
Joefuskie - thank you for posting this.
thumbsup2.gif

I have a 6.0 as well and have been debating the notion of using 5w40 or 0w40 in it.
I have a few oil changes worth from the last Autozone clearance (Pennzoil Ultra - old formula and Pennzoil Ultra Platinum).
Considering you've had good results with the Rotella in various 40 weights, I now plan to use a 40 weight for it's next oil change.
 
Thanks for the replies and suggestions. I'm not comfortable with going any lower than a 5W due to the aforementioned knocking.

I ran Mobil 1 5w-30 for a few consecutive oil changes and the knocking on startup was brutal. Not to say that it's doing any more or less damage than any other oil it just sounded terrible. it also leaked at a higher rate than other 5W-30's I've run.

Originally Posted By: BrocLuno
And a 40 hot is still way thinner than a 5W at cold start. No issue unless the motor rattles ...


Good point. After reading all the motor oil university chapters I've come around to the idea of keeping OP below the "release" pressure.

Bud_ One, how did you like the Pennzoil? My wife's new Cherokee uses platinum 0W-20 mad it seems to suit that motor well. It's only got 15k miles on it though haha
 
Joefuskie - I like Pennzoil a lot and it's been great when used in my old 97' Accord.
I plan on using Pennzoil Platinum 0w20 for my new Civic's first oil change due here in a couple of months.
The next oil change for my 6.0 is not due until Sept . Last couple of oil changes have been on Amsoil Signature 5w30 and Amsoil OE 5w30 . No issues with running either one.
I plan for the PU and PUP to be great and just as good as the Amsoil I have been running.
I'll update as soon as I have changed the oil and put a few miles on it.
 
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Bud_One, I've toyed with the idea of running AMSoil. The high cost has caused me to shy away from it, as my truck leaks oil at the rate of a quart every 3,000 miles. I've finally broken down and ordered an oil sample kit from black stone so we'll see what that shows with the T6
 
Originally Posted By: Joefuskie
Thanks for the replies and suggestions. I'm not comfortable with going any lower than a 5W due to the aforementioned knocking.



Whether an oil is 5W or 0W only affects an oil's performance at subzero temperatures. A 0w40 is just as thick as a 5w40 at operating temperature. Actually, I wouldn't be surprised if a 0w40 would improve low temperature engine knock by being easier to pump. My Camaro has had cold-start piston slap since the day I bought it new. 248,000 miles later, it still has the same cold-start piston slap. I have found that gently revving the engine to ~1700 rpm eliminates the noise until the pistons warm up enough to close the clearance to the cylinder wall.
 
The Rotella line up, including the T6, is hard to beat. I'd stick with the T6 5W-40. It's been a seal "rejuvinator" in my experience. From my 302 to the 598rwhp 2.2l KB 4.6 DOHC Cobra, it's held everything together under some very rough circumstances while always lowering oil consumption and stopping leaks. After nearly ten years of putting it in many things, I'm a believer.

On the other hand, and a tad off subject, my family's 2v 4.6 and 3v 4.6 get the Pennzoil Platinum in 5W-20 and 5W-30, depending on the season. That's the best oil for the 4.6/5.4 family.

Run whatever you like, though. Oil makes us feel better. It's like therapy for the soul lol.

And I don't believe any oil will 100% remove that start up piston slap. Try an AC Delco filter if you haven't, already.
 
Thanks for the replies! I'm going to give the T6 another OCI just to see how things go. I'm thinking I'll try one of the Penzoil products if i feel like switching off of the T6. Thanks again for all of the feedback
 
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