we've used 5w30 for 170,000 miles
5W30 oil.
80W90 gear oil.
6 qts with filter
5w30 in the winter or 10w30 in the summer.
6 qts with a new filter
5W30 in cold weather. 10W30 in hot weather.
5W30 GTX Gastrol is a real good oil to use. Kendell is good to. Factory weight is 5W30
SAE 10w30 any major brand. Use High Mileage oil if it has over 100,000 miles on the odometer.
For a 2003 Chevy Suburban (all engine sizes), the recommended viscosity is 5W30.
85W90 gear oil.
6 quarts of oil.
ph3506