Oil Recommendations

I have 2000 Silverado 1500 Z71 with 4.8 Vortec
Truck has 362,000 miles on original motor. I live in
North Carolina. What weight oil should I be running?

I would suggest something with a weight of around 6.68 pounds per gallon.

The viscosity of mineral oil for that engine was supposed be 5W-30 as I recall. I'd have to check my 2000 truck owner's manual to be sure. The Vortec in that has been running Mobil1 10W30 since the initial oil change at in August of 2000 at 535 miles. The 10W30 synthetic pumps and flows better than 5W30 mineral oil in cold anyway.

It's had a water pump, alternator, two AC compressors, a radiator, starter, two sets of oil cooler lines, and intake gaskets along the way. At 220K it still has the original chain, heads, bottom end, and still doesn't leak from the engine. If you are using synthetic, I'd suggest 10W30 if it will still produce sufficient oil pressure with that. If it doesn't hold at least 20 PSI at 2,000 RPM with a fully hot engine, 40 might be worth trying in warm weather.

Back to that owner's manual, there IS a range of recommended viscosity oil based on temperature. It used to be pretty common to use different viscosity oils in summer and winter, and with a higher mileage engine, that is still a viable option.

I don't know how long the OP has owned the truck, or how many of those miles he has put on it, but at 362K miles, I would keep using whatever oil you have been.

I have 2000 Silverado 1500 Z71 with 4.8 Vortec
Truck has 362,000 miles on original motor. I live in
North Carolina. What weight oil should I be running?

the 2000 Silverado 5.3l 200K miles and the 10-30wt syn oil ....7K miles engine oil the oil stick 1/3 qt ....also the WIX XP OIL FILTER ...

APRIL 2000 NEW ,,, TODAYS ! NO ENGINE AND THE TRANSMISSIONS ...