I just bought a 2000 Silverado Z71 5.3 with 130,000 km on it. I used it for three weeks and it stalled on me. When I went to start it the battery seemed dead so I put the charger on it. It started and said that I had low oil pressure and needed to change oil.It was running rough and it stalled again. I had it towed to a shop and now they tell me there is antifreeze in the oil.Is this a common problem and more then likely is my motor done? I am not happy as I only put on about 1000 km. Any help would be apreciated. Thanks.

If your lucky, it may just be a head gasket.

I had this same problem on the wife's Venture. It ended up being the head gasket and the cause was the orange antifreeze GM uses in their vehicles. It lasts longer than conventional but I think it's more acidic and ended up eating away at the head gasket.

I just bought a 2000 Silverado Z71 5.3 with 130,000 km on it. I used it for three weeks and it stalled on me. When I went to start it the battery seemed dead so I put the charger on it. It started and said that I had low oil pressure and needed to change oil.It was running rough and it stalled again. I had it towed to a shop and now they tell me there is antifreeze in the oil.Is this a common problem and more then likely is my motor done? I am not happy as I only put on about 1000 km. Any help would be apreciated. Thanks.

this is not common on these vehicles.... since you just purchased it it could have been abused/ overheated etc....did you check all fluids the first 1000km... was the antifreeze low ,,,oil off color etc..... stalling at this mileage i would be thinking check the fuel pressures as this is the mileage they fail.....do you know these repair people? if not have vehicle brought to another repair shop to people you know/trust...it could be a head gasket but whats with the oil pressure? what did the dash guage read....40-60psi is normal....normally engine should continue to run .....if antifreeze is in the oil you will have to replace the O2 sensors as well since they get damaged by coolant, if you don't then the cat converters will fail...

I had this oil thing happen with a 6 cyl, but it was because of a intake gasket, but same result, you dont have any oil pressure cause when the dexcool anitfreeze mixes with the oil it turns into a real crappy disgusting sludge and clogged up your oil pump. Go ahead if you want and drain the oil, you'll notice it coming out everynow and then like snot! Sorry to break it to you, but a oil pump replacement is probably in the future too. I tried everything to get mine cleared out, i even ran kerosene instead of oil to break it down, but it didnt work. I hate dexcool with a passion, i alway flush the dexcool and put the green stuff in any GM car i get with a 6 or 8 cylinder engine.

Been a mech. for 25 years and to most that really does not mean anything.But have had to deal with this type of problem[s] many times.I agree that the vehicle has been abused at one time or another..maybe thats why it was for sale at a used lot to begin with.I here in Florida have had this problem with the 5.3 and the head gaskets where eaten away due to the acids in the "100 k coolant" eat at the aluminum and metals used for assembly parts.This coolant should be as any other changed every 3 years regardless of color or smell etc.However,replace the head gaskets and inspect the "bottom end" for any signs of of "hydro-locking" put your fingers on clean top of pistons and twist back and forth,and up and down.Checking for excessive movement and wear and tear on the pistons and cyl. walls as well as the integrity of the rings.Most times the eng. will be alright.Clean as much of the "sludge" as possible.Re-assemble to specs.Upon start-up,leave the oil filler cap off for about an hour without "reving" the engine to give it breathing room to release the extra h2o in the engine.Listen to it carefully.Last note:have the cyl. heads checked by mechine shop![important]

IIRC the intake gaskets on the 5.3 are dry. As in there is no coolant that flows through them. Just a thought.

Thanks for the replies. I bought this truck privately and the previuos owner had a G.M dealer do all of his service work. He told me that he never had trouble with it except for replacing the throttle body. I took it to my mechanic and he said that there is bearing damaga as the mixture must have clogged the oil pump causing the oil pressure problem and the damage. He figures I will need a motor replacement. I had only put 1000 km's on it.:frown: