2001 C5 Vette Recommendation

buster · Mar 24, 2003

A friend at work as recently noticed a piston slap or valve tap comming from the engine. In one of the Corvette forums, someone mentioned that they switched to Amsoil's 5w-30 and the sound went away. He currently runs M1 10w-30.

What oil would you recommend for this car and do you think the heavier 30wt. Amsoil is what made the difference? Thanks.

[ March 24, 2003, 05:20 PM: Message edited by: buster ]

Drew99GT · Mar 24, 2003

Yup. Mobil 1 and LS1's just seem to not get along too well. If it was my Vette, I wouldn't even run Mobil 1 in it. I'd just go with a good 10w-30 conventional with 3,000 mile drains. If he fequently redlines that puppy, perhaps redline 10w-30 would be more appropriate.

Patman · Mar 24, 2003

A lot of it is the viscosity yes. A lot of guys on the Ls1 forums I moderate have piston slap, and many of them solved it with adding 2qts of 15w50 Mobil 1 to 4qts 10w30. Many others solved it by switching to Redline also. Mobil 1's 30wt oils are simply too thin for those engines, period. They need a high 30wt to low 40wt.

By the way Drew, you can't run conventional oil in a Vette, it'll void the warranty if you don't use a synthetic with the GM 4718M rating (even though the same engine goes into the f-bodies and doesn't require synthetics)

[ March 24, 2003, 08:12 PM: Message edited by: Patman ]

buster · Mar 24, 2003

If you take two 10w-30 oils, and one thins down to a 20wt and the other thickens to a high 30/low 40wt., which will still give you better protection, generally speaking? I would think the thinner oil would have a lower HT/HS so the 40wt. would still be holding up better. Consumption for the, now 20wt. would also increase. Is this why Amsoil tends to make there oils thicken rather then thin?
My guess would be thinning=better mpg
thickeng=better protection

The Reason I bring this up is because many high end sports cars that run M1 probably shear down to a much lower wt. oil. A 5w-30 in a Vette that is driven hard is probably running a 20wt. for sometime. Even a 0w-40, which would leave behind "useless molekules" and leave deposits, would wind down to a 30wt. as we have seen.

I guess for price range Mobil falls in, this is the most they can squeeze out of there chemistry in terms of cost and performance. I know I've beat this into the ground, but wouldn't it be a better choice to run a heavier wt.oil in some of these high end cars? Heavier being high 30 to low 40wt.

[ March 24, 2003, 09:28 PM: Message edited by: buster ]

Drew99GT · Mar 24, 2003

quote:

Originally posted by Patman:

By the way Drew, you can't run conventional oil in a Vette, it'll void the warranty if you don't use a synthetic with the GM 4718M rating (even though the same engine goes into the f-bodies and doesn't require synthetics)

Patman, that completely escaped my mind!

Mike_dup1 · Mar 24, 2003

I know persons with LS1 engines and the versions in the trucks and SUV's. Changing oils had little to do with their piston slaps issues. It seemed to be more dependent on anbient temperature.

You can try all the oils you want, it will not slove the problem.

Mike
2002 Trans Am WS6 LS1 (no engine noise yet at 8,000 miles)
2001 GMC 5.3L (has the piston slap issue but once the engine warms up, its gone)

Patman · Mar 24, 2003

quote:

Originally posted by Mike:
I know persons with LS1 engines and the versions in the trucks and SUV's. Changing oils had little to do with their piston slaps issues. It seemed to be more dependent on anbient temperature.

You can try all the oils you want, it will not slove the problem.

Tell that to the many guys on LS1.com and LS1tech.com who have had success with different oils.

Mike_dup1 · Mar 24, 2003

I don't believe it.

A good freind had this problem and has tried many oils and its still there, nothing changed. He used QS, Mobil 1, and some others. I don't think he tried Amsoil, he always hits the quicky places, time it money to him.

I fail to see how the oil can account for piston slap. If it were that easy, why then has GM not come out with this fix? It sure woild save them a lot of critism. I think its just wishfull thinking on thier part. Anyone can say this worked for me and who's to know if thats the truth or not?

I was at the F-body gathering in Bowling Green this past year and almost every F-body LS1 I had a chance to hear start up has some engine noise. Mine probably has it but I am not going to worry about it. My friends 1999 truck with piston slap has many miles on it, last time we talked about it he was in the 70,000 range. No engine work yet but still makes the noise when cold.

[ March 25, 2003, 09:22 AM: Message edited by: Mike ]

Patman · Mar 24, 2003

Whether you believe it or not, it's happening. Many guys were using 5w30 and went to 10w30 and that alone did the trick. Why would they lie?

Our own Bror Jace on here had piston slap on his Honda and solved it from switching to Redline from Mobil 1.

I'm not saying it'll solve it in every case.

And not every LS1 has piston slap either. I never had any piston slap whatsoever in my 98 Formula from day one (with 12 miles on it) until the day I sold it (with 27k on it) I used only Mobil 1 5w30 in it.

[ March 25, 2003, 10:26 AM: Message edited by: Patman ]

icruse · Mar 24, 2003

quote:

Originally posted by Mike:
But how can oil fix a mechanical problem??

I know a Chevy/Olds/Cadillac service manager and I asked him about oil beofe. He said they tried all that stuff and it does not work.
Its amazing sometimes that things mentioned on the www never work in real applications.

Mike,
I used to be a Parts Manager over two dealerships at once (GM and Chrysler) back in the mid to late 80's. Having to deal with the service techs (some are), the mechanics, etc. and all the other various ones you have contact with in the business, my personal experience was that many of these people do not really know that much about oils, just go by their own personal preference.
Not saying this is so for "ALL", but when you have this disease (you know this thing about oil), well then we know a whole lot more than your average driver does.

Good Day,
Steven

Mike_dup1 · Mar 24, 2003

You need to let GM and Ford in on your discovery. It could solve all their problems with the annoying knock aka piston slap.

Peronal experiences are just that, they are by no means proof that something works. For every one that says this works there are 10 that say the opposite.

I am talking from my our and several friends experience, changing brands and viscosity of oils had no bearing on the piston slap issue.

Seeing is beleiving for me and I don't see it happeding to anyone I know personally.

Patman · Mar 24, 2003

Here is one quote I found from one of the LS1 boards:

quote:

I tried Mobil 1 first but noticed the piston slap syndrome at startup got louder than it was with the oil that came with the car new. Right now I'm running Amsoil 5W/30 in it with a K&N hp2006 filter and the noise at startup is pretty much undetectable. I doubt I'll run it to their 25,000 mile drain interval though. I think I'll do an analysis around 10,000 just to ease my mind.

I'll try and search for more testimonials like this later. I figured you would especially like that one Mike, since he mentions Amsoil fixed it.

3 Mad Ponchos · Mar 24, 2003

Mike, engines are not all the same, some have the problem worse than others, so a "mild" fix may take care of a "mild" problem.

Just as the believers can be deceived into believing in a placebo, so can the skeptics be deceived into disbelieving a cure.

Cheers, 3MP

buster · Mar 25, 2003

I'll let you guys know what my friend experiences bc he is going to run Amsoil 10w-30. My guess is that it does make a difference. The valve tap went away when I switched to Amsoil from Mobil 1. It was still there, but barely noticable. Mike, what oils did he try? Amsoil is a heavy 30wt. but others are not. M1 is almost a 20wt. Being M1 is factory fill for Vettes and there is a contract, Chevy wouldn't ever recommend another brand to solve the problem.

What about the protection question from a heavier 30wt.? Wouldn't this be more ideal then a thin 30wt. M1?

[ March 25, 2003, 05:12 PM: Message edited by: buster ]

unDummy · Mar 25, 2003

Engines make noise. Live with it. Get a rice can exhaust or a deafening stereo.

Don't expect oil to fix a broken engine. If there is piston slap or valvetrain noise, get it fixed. Don't these things come with a warranty?

If this issue is common, I'd serious look at oiling system upgrades(more pressure, bigger oil pump, less oil system restriction..........). Seems to me that some domestic automakers need to fire their engine engineers and start over.

I'm glad someone mentioned "placebo". Psychology plays a big role in fixing many problems.

I know a hypnotist who is willing to remove all engine sounds. Don't blame me if you end up quacking or barking. Side effects sometimes occur.
IMO, automakers and dealers should hire one for the service department.

sprintman · Mar 25, 2003

If the Vette was mine I'd try Redline 5W40 and a fair chance the 'slap' would be minimal or greatly reduce IMO.

buster · Mar 25, 2003

quote:

If the Vette was mine I'd try Redline 5W40 and a fair chance the 'slap' would be minimal or greatly reduce IMO.

I 100% agree and would use the same.

Patman · Mar 25, 2003

quote:

Originally posted by sprintman:
If the Vette was mine I'd try Redline 5W40 and a fair chance the 'slap' would be minimal or greatly reduce IMO.

Yep, and I think the LS1 likes oils in the high 30 to low 40wt range the best too.

vettenuts · Mar 25, 2003

GM changed the piston in the Corvette LS-1 in the spring of 01. I have an 02 and recently found they released a "piston slap" TSP for this new piston design as well. Lovely!!!

Anyhow, I am using the Amsoil 5W-30 (ASL) and recently did an analysis on it posting the results here. I am quite happy with it to date. Not only that, but without the M1 jugs at Wally Mart, the price difference at this point is pennies so I have also switched several of my other cars to the Amsoil and buy it by the case of four gallon jugs.

Mike_dup1 · Mar 25, 2003

But how can oil fix a mechanical problem??

My truck makes the noise with 0W-30, 5W-30, 10W30 and 10W40. No difference.

I am not saying someone is lying, it could be they beleive in thier minds this solved the problem. I am saying that if this is the case, its was not piston slap. The fact that it may work for some and not all, is indication to me that is not working. Some don't know exactly what they are hearing, it could be valve train noise and they assume its poston slap.

I know a Chevy/Olds/Cadillac service manager and I asked him about oil beofe. He said they tried all that stuff and it does not work. First it was the oil filters, then is was the oil and after 3 years the noise is still there.

Its amazing sometimes that things mentioned on the www never work in real applications.

[ March 25, 2003, 12:11 PM: Message edited by: Mike ]

2001 C5 Vette Recommendation

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