I have use your MMO for 40 years now and have been happy with it! Now my youngest son (of 6) bought a 2002 Chevy Z71 4x4 with a 5.3 automatic trans.. It has a about 100,000 miles on it.. He got it about a year ago.. When he first got it the oil was just changed.. At 2000 miles or so a lifter could be heard at start up.. I told to change the oil and add some MMO.. (conventional oil) Again 2500 miles later the lifter started making noise. I just changed the oil filter. That lasted about a 1000 miles.. So we switched to Castrol synthetic oil and MMO.. At 2000 miles again the lifter noise.. Changed the oil and more MMO.. Again 2000 miles later lifter noise and some sludge came out this time? The next time the lifter started after 1000 miles in the morning and sometimes during normal driving days? So I switched out just the filter and today after 2500 more miles (3500 total) The oil can out with a lot of thick sludge and the filter has it in there too?? He switch to Valvoline synthetic oil this time thinking it’s the oil??  I don’t think so.. It’s his first truck and he owes a lot of money on this truck.. WE need to make it LAST!  Am I doing the right things with his truck or is there something more we can do?? For my cars I have only use conventional oil and MMO and never had a problem.. Thank you Richard

If you’re seeing sludge coming out, I think two things are happening;

1. The MMO is doing some cleaning.
2. This motor wasn’t properly maintained prior to your son’s ownership, it very well could be sludged up. Kind of explains the lifter noise too.

I think the sludge coming out is a good thing. Likely was there before and now it’s coming out. I would stay the course, keep adding MMO until it gets really cleaned up.

Can you see anything under the oil fill cap? That will tell you something, although I recall on my brother’s old Tahoe that you couldn’t see anything through there.

Panthermike - 04 May 2010 04:44 PM

If you’re seeing sludge coming out, I think two things are happening;

1. The MMO is doing some cleaning.
2. This motor wasn’t properly maintained prior to your son’s ownership, it very well could be sludged up. Kind of explains the lifter noise too.

I think the sludge coming out is a good thing. Likely was there before and now it’s coming out. I would stay the course, keep adding MMO until it gets really cleaned up.

Can you see anything under the oil fill cap? That will tell you something, although I recall on my brother’s old Tahoe that you couldn’t see anything through there.

Good info:  I would continue with the MMO.  It is possible something up top is worn and/or in need of adjustment, I’d do another OCI or two with the MMO.  Used high mile engines are always tricky, especially when the history is unknown.  I’m not familiar with the 5.3L GM engine, but I do know my way around the good’ole 350 sometimes with those, a valve adjustment was in order.

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clutch53crs - 28 April 2010 01:38 AM

I have use your MMO for 40 years now and have been happy with it! Now my youngest son (of 6) bought a 2002 Chevy Z71 4x4 with a 5.3 automatic trans.. It has a about 100,000 miles on it.. He got it about a year ago.. When he first got it the oil was just changed.. At 2000 miles or so a lifter could be heard at start up.. I told to change the oil and add some MMO.. (conventional oil) Again 2500 miles later the lifter started making noise. I just changed the oil filter. That lasted about a 1000 miles.. So we switched to Castrol synthetic oil and MMO.. At 2000 miles again the lifter noise.. Changed the oil and more MMO.. Again 2000 miles later lifter noise and some sludge came out this time? The next time the lifter started after 1000 miles in the morning and sometimes during normal driving days? So I switched out just the filter and today after 2500 more miles (3500 total) The oil can out with a lot of thick sludge and the filter has it in there too?? He switch to Valvoline synthetic oil this time thinking it’s the oil??  I don’t think so.. It’s his first truck and he owes a lot of money on this truck.. WE need to make it LAST!  Am I doing the right things with his truck or is there something more we can do?? For my cars I have only use conventional oil and MMO and never had a problem.. Thank you Richard

Can you tell me what the oil feels like when you rub it between your fingers? Does it have a smell to it?

It’s not the oil, it’s just the jerk who had the car beforehand. Care to guess why the oil was just changed before he bought it? It was changed so that you wouldn’t see how bad the oil (and engine) was. I assume the color of the oil is black again, I would add half a can of Seafoam to the crankcase and drive it another 500 miles or so, then drain it and replace with a cheap oil (Shell, Pennzoil, etc) and MMO (unless you have the cash to use Mobil 1 or Valvoline Full Synthetic). Drive another 1000 miles or so with the MMO until it becomes black again and replace. Keep doing it for the year until it starts to ease up a bit. You have to get that sludge out of there. Afterward, run Mobil 1 Extended and always keep using Mobil 1. It’s a good oil and she won’t let you down.

-Techniker

Souinds like the engine was neglected and it will take some time to clean up.  As mentioned it isn’t the oil, it is how the vehicle was maintained.  It is possible that the lifters need adjustment, or the cam lifters might need replacement. Hang in there with the MMO, sounds like there is a lot of junk in that engine, and it is going to take some time to get it out.  In the mean time I would use a good dino oil until I get it clean, save the synthetic oil for after the engine is cleaned up.

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