Oil weight

Mike GMC · March 7, 2018

So this is NOT intended to start any oil brand debates. Those have been beat to death. My question is, what weight oil is best for the 5.3? I know the factory recommendation is 0w-20. This seems awfully light to me. The previous 2 generations had 5w-30 recommended. What's different in the Gen 5 that makes the lighter oil adequate? Or would 5w-30 extend engine life in exchange for a bit of mpg loss?

1SLOW1500 · March 7, 2018

So this is NOT intended to start any oil brand debates. Those have been beat to death. My question is, what weight oil is best for the 5.3? I know the factory recommendation is 0w-20. This seems awfully light to me. The previous 2 generations had 5w-30 recommended. What's different in the Gen 5 that makes the lighter oil adequate? Or would 5w-30 extend engine life in exchange for a bit of mpg loss?

I believe it is light also. I also believe it is a part of the issue of the oil blow by. Look at the catch can videos. And even shops are servicing the oil in the intake.

Sent from my SM-N950U using Tapatalk

Mike GMC · March 7, 2018

It could be contributing to the blowby and oil in the intake. However, my 08 caddy CTS with the 3.6 GDI used 5w-30 and it needed the catch can desperately. That's probably one of the top reasons I traded it for my current truck with only 111k on the clock.

Ozer · March 7, 2018

Just a heads up on oil deal from AutoZone, different weights available.

5qt Mobil 1 oil + Mobil 1 extended performance filter = $29.99 and there is a $17 rebate. Limit 2.

I got 2 sets and after rebates they come to about $15 with tax.

https://www.autozone.com/deals/dealMaker/dealMaker.jsp?dealId=92443&showDealMaker=true&intcmp=20180306_20180402_dlp_spotlight_Mobil1-OCS

Carry on...

Edited March 7, 2018 by Ozer

Donstar · March 7, 2018

Interesting question. I remember thinking 5/30 was too light! My 4.3 uses 5/30. If I use 0/20 will it go faster? I don't spend time anymore second guessing the manufacturer's reason for such things. Their reasoning probably has better foundations than my knowledge on this subject. I wonder if deliberately using non-recommended oil could create potential warranty challenges...

Kubs · March 7, 2018

The owners manual says Dexos1 or equivalent. As long as the oil meets that spec it cannot void the warranty.

The Corvette owners manuals state to use a higher weight when tracking the vehicle due to heat. I guess if you do a lot of towing you can step up to a 30 weight.

diyer2 · March 7, 2018

My 93 Silvy, 5.7L, TBI, 4l60E, 373 gears owners manual recommended 5w30.

I bough it used with around 40 k miles on it.

I switched to 10w40 at 100 k miles.

It cut down on the oil usage.

Drove it for another 130 k miles.

Towed a 4 k pound boat and the bed loaded full of food, beer etc. from Denver to Lake Powell via I -70 just before I sold it.

It used half a quart of oil round trip.

sdeeter19555 · March 7, 2018

Interesting question. I remember thinking 5/30 was too light! My 4.3 uses 5/30. If I use 0/20 will it go faster? I don't spend time anymore second guessing the manufacturer's reason for such things. Their reasoning probably has better foundations than my knowledge on this subject. I wonder if deliberately using non-recommended oil could create potential warranty challenges...

It might get better mileage with 0/20...my guess is it's a CAFE thing.

Sent from my SM-G950U using Tapatalk

Mike GMC · March 7, 2018

I would think that as well, but the question is, are sacrificing any long term engine life in the name of a few tenths of a mile per gallon?

garagerog · March 7, 2018

Back in the days of dino only oil GM specifically recommended against the use of 10-40W oil. I believe their reasoning was that the more viscosity modifiers you had to add to oil, the less actual lubricant you have. Additives have no lubricating property on their own, so the addition of more viscosity modifiers, anti-foaming agents, anti-corrosion agents, detergents, et. al. results in a lower percentage of actual lubricant. Synthetic oil by nature resists viscosity break-down, therefore I assume less of a viscosity package is needed. Just supposition on my part but that's why I believe you see a wider range of accepted viscosity ratings for synthetic oil. My brother went to the dark side about 3 years ago and bought a 6.4l Hemi Ram to pull his 35 ft. TT, he's told me that 0-40W synthetic is what's called for it and he has trouble finding it locally and so he buys it on Amazon. 0-40W sounds crazy to me, but what do I know.

diyer2 · March 7, 2018

The manual for my 93 warned to not use 10w40.

That truck had dino oil only.

I still believe spec oil, a decent filter and no extended change intervals is key.

redwngr · March 7, 2018

Proper journal bearing flow requires the oil be thin enough, but not too thin.

The recommended viscosity was selected to match the bearing design and expected temperatures.

Grumpy Bear · March 7, 2018

Tricky question.

2 hours ago, redwngr said:

Proper journal bearing flow requires the oil be thin enough, but not too thin.

The recommended viscosity was selected to match the bearing design and expected temperatures.

redwnger makes a HUGE point. Heavy on the EXPECTED. This does not mean ambient air temperature but actual bulk oil temperature. You pull 50 degrees out of the normal peak operating temperature with a cooler and your *W30 just became effectively a *W50.

I've been running 40W in my Harley(s) for over a decade...with twin coolers with nary a whimper. I run 20 in the 4.3 and use none. Use a colder thermostat thus colder bulk oil temps. Not a thing one does half cocked. I've run 20 weigh in Honda's that were designed for 30 for over a quarter million miles without using a teaspoon.

Edited March 7, 2018 by Grumpy Bear

seamus2154 · March 8, 2018

0/20 along with the trans, and synth rear fluid are all for fuel mileage. On my 1st 2014 Silverado 5.3 I went in for my free oil change, that came back with a dent. (so didnt do that again) On my receipt it said 5/30 dexos ? I asked, they told me in Florida that was all they used? I have done oil analysis using 5/30 since 2014 to date on 4 trucks and it is perfect. My catch can catches less. I also do not use the thin crap they use in the rear diff. I use Amsoil Sever gear. I have not lost any fuel mileage at all. I am in a tropical climate so cold start up is of no concern to me but if I were up North I may use 0/20 for winter.

Mike GMC · March 8, 2018

6 hours ago, diyer2 said:

The manual for my 93 warned to not use 10w40.

That truck had dino oil only.

I still believe spec oil, a decent filter and no extended change intervals is key.

When you say "extended change interval" are you suggesting a specific interval, or just not exceeding the oil life monitor?