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I've used 15-50 in all my forged LS motors.
an 05 and 2 z06 08&09. All used 15-50. My last motor was forged LS 7 made 700 hp. Never had a problem. I'm running 10-30 in my 16 Z06. It makes 630rw/635rwtq. It's a daily driver. I live I so cal. I would like to run 15-50 year round as I did in my C6's. Is there a downside I'm not aware of? Other than the loss of a little hp.
Last edited by andreas g.; 10-18-2016 at 11:06 PM.
Reason: Misspelling
This is a great question and I'm certain you'll get answers all over the place. If you've live thru the 60's muscle cars and into the early 70's, it was common place to ignore the manufacturer's recommendations and run different weight oil...and most often, you ran a heavier oil, like 20W50, instead of the recommended 10W30. Yep, most all of us did it, after all, heavier had to be better for the engine, right? Maybe OK then, but now you could be asking for trouble on a basically stock engine used as a daily driver and track'd every so often. As a daily driver, my advice would be to use the factory spec, Mobil One (or equivalent synthetic) 10W30. Track applications I really don't know personally, but I've seen heavier oils like 15W50 or 20W50 recommended by the Forum "experts". Don't forget, those GM engineers that designed this engine probably know what they're doing, given the constraints of a large corporation like GM. In 2016, heavier isn't always better.......
Your giving up some HP and fuel economy. Along with plenty of upper cylinder wear because the 15-50 doesn't flow or lubricate near as well cold as the recommend 5 -30. So your top end is waiting longer for lub. Plus runs too much pressure when cold. I don't think your helping your engine. These new engines have tighter clearance's as well. They need the 5-30. That is why they recommend it. Only need the 15-50 when it gets really hot then it maybe better otherwise no
I wouldn't do it!
I would say that if you live near the Equator (where it's hot all year long) you would be ok.......even recommended. However, SoCal gets cold in the winter also so you're better off with the oem spec oil. Use a magnetic oil plug also.
Tadge answered the question about full time 15W50 usage here. In short, it is not recommended for full time usage, mostly because of the threat of operating the car in extremely cold weather.
Given what the owners manual clearly states, running 15W-50 in your motor on the street could give you warranty problems if you have a lubrication related warranty claim.
As previously stated, the owners manual specifies particular oil viscosities for a reason. Why mess around with it?
Not to confuse it more but the GT500 I just sold used a 5W50 oil. Wonder why Chevy didn't test that sort of oil.
On a totally different note, it is a little known fact that Mobile 1 oil does not work well with leaded fuels (makes sludge). For a short time there was a Mobile 1 for aviation use (leaded fuel application) and it was discontinued because the combination of leaded fuel and Mobile 1 was awful. Not a big deal unless you track the car and run C16 or other leaded fuel.
Tadge answered the question about full time 15W50 usage here. In short, it is not recommended for full time usage, mostly because of the threat of operating the car in extremely cold weather.
Actually what Tadge didn't say was the most important part of that message. He didn't say that engine damage would occur. He only said GM didn't recommend it because it would reduce fuel mileage and increase their catalytic converter warranty claims. If they recommended it on the street then they would have to reduce their certified fuel mileage.
As for the old days we ran straight 10 weight oil in the winter and straight 30 weight in the summer with the changeover coming somewhere in the late March and late November time periods. When you were changing oil 4 times per year it wasn't a big deal to make the changes then.
Actually what Tadge didn't say was the most important part of that message. He didn't say that engine damage would occur. He only said GM didn't recommend it because it would reduce fuel mileage and increase their catalytic converter warranty claims. If they recommended it on the street then they would have to reduce their certified fuel mileage.
As for the old days we ran straight 10 weight oil in the winter and straight 30 weight in the summer with the changeover coming somewhere in the late March and late November time periods. When you were changing oil 4 times per year it wasn't a big deal to make the changes then.
Bill
I agree Bill. I do not operate my car in the extreme cold weather applications for which the 5 weight oil would be necessary. I took Tadge's response to be a very well-worded response that there is nothing wrong with 15W50 if you do not drive it in cold weather. The rest of his answer said that the track weight oil was not validated due to additional additives, but that does not scare me any. Here in Oklahoma, I will use the 15W50 in the summer and 5W30 in the winter.
I think it depends on what color Z06 you have. Red and black you would be okay. White,blue,silver,grey you should never run it. Yellow can go either way.. Hope this helps..
Take a look at the temps where you live and then this chart, should give you a rough idea. Generally motors are built to tighter tolerances than 40 years ago so err on the side of thinner, I would say.
I'd be hesitant to fire up my car with 15W15 on a -10C day, which is about the ragged edge according to this. Basically if you never get below 40F I think you're fine.
I run 10W60, per manufacturer recommendation, in my M3. That's an even wider range, and it's an expensive oil too. But I run it year round (rarely below freezing here and it's a convertible so I'm unlikely to drive it in real cold).
What a load of crap that statement is. The oil gets through out the engine in the same time period. You act like 15/50 is 90 wt gear lube. Compare the two oils in question sometime. I am not wrong but why argue with someone who cannot think for himself. Use your brain. If using 15/50 at the track damaged the engine then that would void the warranty or does gm have you preheat the oil before starting the car like they do with the race team corvettes. Synthetic oil is thin as it is and the starting viscosity of 15 is not exactly thick oil at low temps.
What a load of crap that statement is. The oil gets through out the engine in the same time period. You act like 15/50 is 90 wt gear lube. Compare the two oils in question sometime. I am not wrong but why argue with someone who cannot think for himself. Use your brain. If using 15/50 at the track damaged the engine then that would void the warranty or does gm have you preheat the oil before starting the car like they do with the race team corvettes. Synthetic oil is thin as it is and the starting viscosity of 15 is not exactly thick oil at low temps.
Your still so wrong that why they use the 5-30 is a better oil for the engine.
15-50 will not move as well cold and you will be lacking for top end lub on a cold start. Then you can just button your lips if you cannot debate without name calling!
Let me tell you something we don't need someone going around using 15-50
full time because they read on the forum it is a good idea.
The only time you use 15-50 in your car is when you will reaching high oil temps like 250 and above. (LIKE AT THE TRACK) Other wise it is too thick and costs power and MPG more the .1 you said. Otherwise if you were right GM would just recommend it fulltime but they don't. They recommend againest it. Might cost you your warranty as well if they find 15-50 is used full time.
THUS the 5-30 on the fill cap!
At the standard 200 oil temps 50 wt is just wrong. And that's what 15-50 is when it warm a 50 wt oil!
To add to your post, the additional additives are zinc and phosphorus in the form of higher levels of ZDDP as an anti-wear additive. The higher level of ZDDP reduces the life of the catalytic converter causing an increase in warranty claims (as Bill Dearborn said) as the EPA requires manufacturers to warranty them to 120,000 miles now.
The 15W-50 has significantly more of the ZDDP anti-wear additive which more than offsets the few milliseconds longer it takes for the 15W-50 to get everywhere than the 5W-30. From there, the extra ZDDP continues to provide protection against wear that the 5W-30 can't...the issue isn't a wear issue, it's a catalytic converter warranty claim issue as Bill Dearborn stated above. Please go do more research, you're way off base on this.
I was talking 15 -50 vs 5-30 which I am right! Of course I may not befiguring the extra ZDDP because another 15-50 may NOT have it and the 5-30 is what is recommend for good reason the 15-50 track oil is used for the high oil temps and 50 wt is not needed at 200 degree's which is what you would expect for oil for street use. Not off base at all just was talking more in general terms not just the Mobil 1 15-50. GM doesn't want you using it either full time too heavy for all around use. ESP in cold weather. Try your 15-50 in cold weather. We were not considering the outside temps either.
I don't think you would run it full time either. Then Tadge is not an expert on the oil subject either. He is not the guy who determines which oil is recommended GM has others for that.
10-18-2016, 11:00 PM
Full time use of 15-50 M1 oil
We were not considering the outside temps either.
