Running a heavier oil

Nobody has asked what your hot oil pressure is yet.

I don't trust dash gauges for some circumstances but if its in the normal range and moves normally for various temps and RPMs then oil viscosity is not your problem.

If your oil pressure is normal, You could try a 20w50 or Lucas... but if it makes a difference in your noise then you definitely have a problem that will fail eventually. Its a single component that is failing, not 'just tired' like what makes most people switch to thicker oil.

Edit, if you want the best... Amsoil makes a 5w50 oil, that could be the best of both worlds for you. albeit expensive.

I always throw in one quart of Delo 15w40 when I change the oil in my old '88 Chevy truck. The extra detergent in the diesel oil seems to help in keeping the lifters very quiet.

Komet said:

Whatever-40 after 180k miles is fine if you like seeing the needle go up more. Maybe don't run it if it's below freezing out. MMO might fix your lifter tick, the thicker oil won't. Diesel oils have a different additive package that isn't appropriate for your motor but you can run it anyway if you like. Snake sauces only sometimes work on the right kind of neglect-related issues, and never on mechanical failures.

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I like Mobil1 0W40 year 'round. If they come out with a -5W40 I'll switch to that. The dually gets the oil pretty damn hot, it exists to work and is rarely driven empty. The 1500 gets it as does the Camaro, and the Camaro is a road race car.

One more for running RT6 5/40 in 350’s. No problems. Helps when they are older, bearing clearances / oil press etc. I’ve used it in other engine as well, good oil.

I’ve also used MMO on lifters. Sometime worked, sometimes didn’t.

My old Yukon (170k miles) has been on 5/40 Rotella T6 for several years. No issues with the cat. Although, I do prefer Mobil1. But that’s a debate for someone else..

Supercharged111 said:

I like Mobil1 0W40 year 'round. If they come out with a -5W40 I'll switch to that. The dually gets the oil pretty damn hot, it exists to work and is rarely driven empty. The 1500 gets it as does the Camaro, and the Camaro is a road race car.

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If it's thin enough to flow good volume when it's cold (for your climate's definition of cold), then it's good. I'm probably still spooked by ancient internet gossip about shear strength being affected by the large split technology synthetics, but a 0w should be very fine at freezing temps on paper. I had 15w-40 Rotella in mind about the freezing comment, then again I ran that year round in the 'ol 255k Jeep 4.0 I6 and it did just fine.

Komet said:

If it's thin enough to flow good volume when it's cold (for your climate's definition of cold), then it's good. I'm probably still spooked by ancient internet gossip about shear strength being affected by the large split technology synthetics, but a 0w should be very fine at freezing temps on paper. I had 15w-40 Rotella in mind about the freezing comment, then again I ran that year round in the 'ol 255k Jeep 4.0 I6 and it did just fine.

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From what I understand large splits can be an issue for dino oils, but not for synthetics. A dino oil breaks down and reverts to the lower weight whereas a synthetic reverts to the higher weight. How a group 4 base stock acts though I can't say, and they're the majority of synthetic oils out there. I don't ever see my oil pressure fall off the face of the earth prior to an oil change, so I don't worry about it.

Rollybear1 said:

Hello everyone, 98 GMC K1500, 5.7, 184K miles. My Truck runs well but has the annoying lifter tick. When I cold start it, it doesnt tick at all. After approx 10 minutes and the engine temp starts getting to 175 or so the tick starts.
Im 99% certain its not a leaky exhaust gasket. Sound is coming from center of engine and well, under the intake. Pretty much where the lifters sit.
I'm thinking of running Marvel Mystery oil through it and then trying a heavier oil.
I live in utah so winters are cold, so I was thinking a 10W-40? Does anyone know if a 5W-40 Diesel oil will hurt anything? and what exactly is the difference between diesel oil from gas engine oil?
Any other suggestions? Like I said it runs good but is just an annoyance with the tick, tick, tick at stop lights and in parking lots.
thanks!!

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Like others, I've also run diesel Rotella T6 full-syn 5W-40 for years; it never fouled any cat or sensor because it doesn't contain a great deal of Zinc or Phosphorus. As another gent here said, most diesel oils these days also have less Zn & P.

FWIW, lotsa Subaru flat four hotrodders swear by T6 5W-40.

If ya don't like the "diesel" label ... Castrol Edge full-syn 5W-40 on walmart shelf (5 qt jug unlike 1 gal Rotella) and it's Not diesel-rated or marketed as such. I've run it as well; and in your 5.7 Vortec V8's little brother (Vortec V6 4.3L).

If ya wanna wreck a weekend, you could pull intake off and remove lifters; disassemble each lifter individually and clean with acetone or lacquer thinner etc. Close inspection too; rule in or out any damaged wheels/rollers etc and cam lobes as well. Inspect PushRod ends for any fractures. Possible you might see source of ticking under close inspection of lifters & lobes & PRs. Perhaps consider the work as an opportunity to replace a weeping intake gasket ? Please do Not replace lifters with Made in China. Elgin offers made in North America for small $ ... even when new, recommend disassemble & clean as above.

Supercharged111 said:

From what I understand large splits can be an issue for dino oils, but not for synthetics. A dino oil breaks down and reverts to the lower weight whereas a synthetic reverts to the higher weight.

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It is independent of base oil as the viscosity improvers that 'create' multigrade are long chain polymers added to the oil.
Mineral oils are better at absorbing additives than synthetics are so if the quantity of viscosity improver added is of consequence, the advantage is with the mineral oil.

Running a heavier oil?

Don't do it. Additives only degrade an oil's ability to be an oil. Look into "540rat" and his oil ranking list. He's got several oils rated on their own plus the same oils with additives- the additives often cut the film strength of the oil in half. Pick one of the top contenders in 30 weight flavor and call it good. This is coming from a guy who swore by Rotella T6 and ran it in everything.

Fun fact; Oil does not come from Dinosaurs.