What kind of oil to use 1999 suburban?

Answer 1

It depends entirely on the condition of your engine. If the bearings are in good condition, use a lighter weight oil (lower numbers). If the bearings are getting a little worn, use a thicker weight oil (HIGHER numbers). Watch the oil pressure gauge. If, after the engine warms, the oil pressure starts to drop to near zero during idle, use a thicker oil. If the oil pressure stays up when the engine is warm and idling, you might be able to use a lighter grade oil. As related to the brand, use whatever has been running in the engine in the past, so long as it's a respected brand with the SAE certifications.

Answer 2

5W30 in the winter time. 10W30 in the hot months.

Your engine has a roller valve train in it, and if you run heaver oil, then the engine will not lube and it will burn the valve train up.

Answer 3

Winter time - 5W30 GASTROL GTX Summer time - 10W30

Answer 4

5W30 GTX GASTROL is a real good oil. 10W30 in the hot months.