Just shortly after a recent oil change I have noticed what sounds like valve/lifter tapping for about 30 seconds, but only on the first start in the morning. The outside temperature today was about 40 degrees. What concerns me is the mechanic put a sticker on my window which indicated the next oil change in 3 months. The service manager assured me that Mobile 1 synthetic oil was used --- just a mistake on the technicians part with the window sticker. Hmmm. Question: is this short-lived tapping noise with a cold engine in the morning somewhat normal? Should I visit another dealer and have the oil changed again just to make sure synthetic oil was used? I only have 8700 miles on the car.

 

The tapping noise is indeed valve train noise on start-up. Chevy has had this issue for some years now with several differing engine platforms..but is completely normal depending on how long the engine has sat and the nominal temperature of the engine etal when started. But, one of the aspects of synthetic oil is it's ability to stay on engine parts after shut-down which synthetics are better at. This reduces this noise but does not eliminate it.

As far as the dealer is concerned.... and the "iffy" oil change problem is completely up to you. You will NOT harm your engine by running non-synthetic per se, but under dire conditions I would want mine to have all "true" synthetics (made from group IV base stocks such as Mobil One) on board.

 

That was a great answer. I'll monitor the problem and see how it goes then. Thanks for the information.

 

I notice some momentary cold lifter noise on my '05 with 19,000 miles also.It doesn't do it on every start-up but occasionally after the car sits for a few days or so I'll hear it.I'm sure 5W cold viscosity oil doesn't help either.

 

Thanks --- then I know it may not be abnormal and others have experienced it as well.

 

If noise is not Heavy, only occurs on a cold engine and goes away, not a problem.

It appears most shops & mechanics put on 3 month stickers every time they do an old change. Old habits die hard.

If you have Mob1 in there let the DIC be your guide or once a year.

 

Roger that --- thanks.

 

I've had this and at times it was really loud and lasted a while. I had to shut off and restart a few times. Turns out GM knows about this problem. Air is getting in the lifters and allowing them to bleed down at times. They still haven't come up with a fix for it though. I haven't checked to see if there is a TSB on it though. Anyone know?

 

Dunno if the LS2 and LS3 have the issue but piston slap is not all that uncommon in the LS6 (C5 Z06).

My '02 Z06 has piston slap for about the first 30 seconds when it's first started but hasn't created any problems for 70K miles.

The easiest way to tell the difference between piston slap and valve train noise (a leaking down lifter) is that piston slap will be more pronounced under load. It will also go away in short order as the piston warms up and expands a bit.

 

Good to know this.

 

Time it, is it really 30 seconds? If it's more like 5 to 10 seconds, likely just a lifter or two pumping up.

Started after an oil change...hmmm. I wonder if their stuff was **** thin. I run into that a lot with Harleys. Somebody will take their bike to a dealer and think they are getting getting the greatest oil change on earth by asking for synthetic oil. And the dealer puts in their version of water thin synthetic. And on the first cold start of the morning, the lifters knock for about 5 seconds (and Harley's use Chevy roller lifters). They'll go back and forth arguing and doing nothing, and then when I put 20w50 V-twin synthetic in it - no more knocking. Some oil is just way too thin for that application.

If a dealer is using bulk oil, who really knows what is in that barrel. If your in a warm climate, it wouldn't hurt to use a Mobil 1 or Amsoil 10w30. or any brand 10w30 synthetic with the GM corvette spec (4918 or something like that). The 10w30 will be a hair thicker, maybe the lifters won't bleed down quite so much.

What happens is, when you shut the motor off, there are going to be a couple lifters up on cam lobes. That several hundred pounds of spring pressure over time will bleed the oil out of that lifter. The thinner the oil, the easier it will bleed out. As the engine breaks in, the lifters now wear into their bores - now there is just a slightest bit more lifter to lifter bore clearance to allow oil to bleed out over an extended period of time of that lifter sitting up on the lobe with spring pressure against it.

That's why a brand new, super tight fresh motor may not do it, but one with 10K or so on it will. Performance cars with stiffer valve springs and taller cam lobes are also much more noticeable.

If it goes away real quick, within 10-15 seconds, most likely just those couple of lifters that bled down refilling. You can listen with a stethescope and see which lifters are doing it. If it is different lifters each morning, no problem. If it's the same lifter every cold start, I'd wonder about that.

Since in started with an oil change, just for kicks, I'd redo the change with 10w30 Mobil 1. Or it could be that the old oil in there was thicker than dog snot from not being changed in a long time. And now the new oil is the correct viscosity and just making it more noticeable. I've seen that before. Take oil 10K and beyond, I've seen it come out real thin or real thick, high miles on oil can make it do funky things. How many miles was on your old oil.

This is where the oil gods will disagree and say today's oil can go xxK miles.... They also probably don't change their own oil and look at what comes out. I just changed my girlfriends Equinox oil when her change oil light came on, I think hers came on around 11,000 miles. What came out had little similarity to oil, looked like dark brown thick pancake batter coming out. No thanks for my cars, I'll stick with around 3 - 6K range for changing oil.

 

I've got piston slap in my 02 Denali, (6.0L) and noticed maybe a year after purchased. Had it in to the dealer and 'no fixey'. They contend its not a problem. Have not heard it on my '07 vert, but would not be surprised if it shows up sometime in the future.

It lasts longer in colder weather, fews seconds to maybe 15 or so.

If I understand correctly the leaking lifter would be the same regardless of outside temp.

 

[QUOTE=Michrider;1568701334]Time it, is it really 30 seconds? If it's more like 5 to 10 seconds, likely just a lifter or two pumping up.

Now that’s interesting. I’ll time it tomorrow morning and see how long it actually lasts. As I previously stated, the car only has 8700 miles on it and the first oil change was done at 7500 miles. I think I may go to another dealer and have it changed again when it hits 11500 miles ---- just in case the first dealer screwed up.

 

For those who are unaware they'll be happy to charge for an oil change every 3 months!

 

change your own oil then you know whats in your motor..

 

Its really the only way to know for sure....