Ever since I bought my 2001 Z28 I have heard a taping noise comeing from the motor almost like a valve tap. He said it was the bigger injectors taping but I know what that sounds like and thats not it. The car just turned over 19000 miles so there really isn't any wear and tear except that the previous owner never drove it and it set for weeks at time which I know isnt good. I used Mobil1 5W 30 until someone told me to run 10W 30 and it seems like the tap is gettting worse both cold and hot. I am starting to hear it now even at low speeds. Anyone have any ideas, its starting to worry me.

 

Some claim it's piston slap, others say ticking from the valves, recently a guy has found the noise to be coming from the coils. In any event, the LS1 makes noise. I wouldn't be running 10W-30 though. Especially not during the cooler time of year. A lot of us use either GC 0W-30 or Amsoil 0W-40. Many have found Mobil 1 5W-30 to be a little thin @ higher temperature. Try the Amsoil. I'd bet the sound is reduced.

 

10W30 should be fine. Its even in your owner's manual. GM doesn't even suggest 5W30 until its well below freezing.

As far as slap goes, my engine is pretty bad when cold and its currently around 25F in the mornings now. If its slap it does take a long time to go away fully while running in cold weather because no matter how warm the engine gets the inlet air temp is still cold and piston temperatures are really affected by the inlet air temperature. But it should go away, you might have to drive the car for 15 minutes before all traces of it are gone. If not it sounds like something else has happened.

 

Yah, GM doesn't recommend changing plugs for 100k & they don't worry too much about transmission fluid care either. The bearing tolerances in the LS1 are close. If you love your LS1, don't put 10W-30 in it when it's cool outside. The whole concept is to allow lubrication when the engine is cold & to keep it well lubricated after it warms up. The UOA's from German Castrol 0W-30 have shown the best engine wear results. Amsoil 0W-40 is another good choice. There are several other oils suitable for your purpose. Go to the Bobistheoilguy web site & research oil tests (UOA's). Then decide on what is the best for you.

 

GM has a vested interest in reducing the wasting of motor oil. They also have people spending entire careers on oil selection. Your owners manual is the result of millions of dollars and many years of design knowledge. I won't knock people for wanting to use synthetic oils but I have never seen any engine ever fail from using non-synthetic. I do not run a fleet where oil wear testing helps squeak out a few dollars every month. My engine will make to 100,000 miles running with crap oil if I tried it. 10W30 is will not harm your car, saying it will is not a credible statement. Personally I will use 5W30 once the temperature is staying below freezing but only because winter for me means -30 or colder at times.

If the original poster's car does simply have piston slap, do not use synthetic. I have tried the German Castrol, Royal Purple, and Amsoil. They all make slap sound worse. Synthetics viscosity does not rise at colder temperatures like a dino oil so the drag on the rod bearings is lower. In a slap prone car this makes the noises a lot worse. I tried them all and went back to dino oil and none of the synthetic oil proponents will try to tell you that the engine's life will be shortened. I don't think we know what the original posters problem is yet but if its slap 10W30 dino oil will help.

 

I have tried RP, GC 0W30, Dino 5W30, and M1 5W30. The Amsoil 5W40 I am running now has by far quieted down the piston slap on cold startup vs. the others. It is almost totally gone. Also my car is kept in a heated garage, the temp. never gets below 50 degrees, no matter how cold it is outside. However the Amsoil flows very well in the cold and I am sure it would be fine for your application. Give it a try!

 

Just curious, have you tried other Amsoil viscosities? I tried the 10W30 Amsoil. While it was the quietest of the synthetics, cheap Pennzoil 10W30 was a bit quieter for me.

 

First, letting the car sit for weeks at a time is not going to cause the motor or valve train to be damaged or to tap/knock/tick or anything else. Of this, I am 100% sure. My nearly 8 year old Z28 has only 13K miles on it, so clearly it sits a lot (all winter actually, and quite a lot even during the good seasons), and this has not caused any issues with the motor.

LS1s are noisier than many other motors. Without hearing your noise in person though, it’s basically impossible to tell if it’s normal or not. As stated, everything from the valve train, to the injectors, to even the EVAP purge solenoid tends to make some ticking even if nothing is wrong. Piston slap is another issue that some LS1s have, this might be your issue if it is more like a “tap” than a “tick”.

Secondly, there is absolutely nothing wrong with using 10W30 oil in an LS1. It’s not going to harm anything, and your motor will not suddenly explode after 30,000 miles because of it. That is all I have ever used in any of my LS1 cars, in fact, without any problems at all. Granted, I never drive them in the winter months, and if I did I would then switch to the 5W30 when the temps are cold. But for running the motor in outside temps above the freezing mark, 10W30 is just fine.

I don’t have an owner’s manual in front of me at the moment, but as I recall, both 5W30 and 10W30 weight oils are approved for LS1 use, only difference is the 10W30 is not approved for use under 0* F.

I like M1 10W30. It’s easy to find at any store, and it works just fine for me. Even when the motor is hot, oil pressure seems to be better with 10W30 over the 5W30 in the same brand, which is why I stick to the 10W30 so long as the weather is warm.

 

never heard of amsoil, is it a top brand, synthetic or non and can I find it as easy as other brands?