How to Change Your Oil
Updated April 19, 2016
You'll need the above tools and supplies to change the oil in your Hummer. Get a drain pan that can take 2 gallons, a funnel, an oil filter wrench, a 15mm wrench and a grease gun. I'm not too particular about the type of grease. I'm using Jet-lube Alco-EP 73 Plus which is a multipurpose high temperature water resistant red colored bearing grease. The grease is formulated to be used in high moisture areas including subsea applications. Jet-lube's claim to fame is lubricants for oil drilling. They are of course located in Houston, TX. Since I started using it I have had very good results which translates into reduced wear on all the greasable parts such as ball joints, tie rod ends and U joints. You can also buy a good quality name brand grease at the auto supply store. AMG recommends NLGI-LB grade chassis grease. You will need 2 gallons of Shell Rotella T or equivalent motor oil. Make sure the oil is for a diesel. Get a Delco PF-1218 oil filter. I also like to have a box of good quality paper towels around and some old newspaper, rubber gloves and a creeper..
The 6.5 N/A takes exactly 8 quarts (with one oil filter) and the 6.5 TD takes exactly 7.5 quarts. I throw in 8 quarts when I do my 98 turbo diesel.
It's always better to drain the oil when it's hot because it flows better rinsing out more of the old oil. Take the truck for a ride and warm it up or change the oil when you get back from a drive. Spread newspaper out on the garage floor under the drain plug and oil filter area. Put your drain pan on the paper and carefully unscrew the drain plug with the 15mm wrench. The oil will be hot so be careful it doesn't spill all over you. That's why I like the rubber gloves.
While the oil is draining unscrew the oil filter using the filter wrench. Make sure that the drain pan is under it because oil will pour out as you loosen it. Take a clean rag and wipe down the area where the oil filter screws in. Take your new filter and coat the rubber gasket with oil and screw it onto the engine until the gasket touches the sealing surface. Tighten it one turn after this. If you over tighten it will squeeze and distort the rubber gasket causing leaks. Wipe the oil off of the filter and the surrounding area. Wipe the the drain plug off and clean the oil pan where the plug screws in. Screw the drain plug in and snuggly tighten it. Don't over do it or you will strip the threads. Some drain plugs have a little rubber gasket. Wipe all the excess oil off of the bottom of the truck.
Open the hood and find the oil fill tube. Remove the cap and wipe the tube and cap off with a clean rag. Using the funnel pour in 2 gallons of oil. Pour slowly or the oil will spill all over the place. I like to wrap some rags around the filler tube to catch any oil that overflows or misses the funnel. I put a little oil on the inside of the cap so it's easy to remove the next time. Wipe up all the spilled oil. Start the engine in a ventilated area and check your oil pressure gauge. As the oil filter fills up the pressure will go from 0 to 30 / 40 PSI (approx). While the engine is running go under the truck with a light and check for oil leaks at the filter and around the drain plug. Shut off the engine and let it sit for 5 minutes and check the oil level on the dipstick. Don't worry if it shows past the full mark. The oil in a diesel will turn black shortly after changing it. It's just the ash from the diesel fuel burning.
Pull the newspaper and drain pan out from the bottom of the truck and pour the drained oil into the 2 empty oil containers and dispose of properly.
Go back under the truck with the grease gun and some rags and pump a few good shots of grease into each fitting. I pump grease into the fitting until I see old grease seeping out. The exception to this are the telescopic slip joints on the front drive shaft. If you pump in too much grease you will pop the cap off the end. Wipe the fittings off with a rag before and after you grease them so you don't inject dirt into the joint. There are 26 to 27 grease fittings.
Some of the fittings on the drive shafts and U joints won't be rotated toward you. You can either move the truck or put the transfer case in neutral, jack up one wheel and rotate it until the grease fittings appear. You'll need to do this for the front and the rear.
The Forgotten Fittings
Don't forget the fittings on the steering column. Many steering complaints can be traced to these joints not being maintained. There is one under the hood embedded in the steering shaft ujoint that requires you to start the truck and turn the steering wheel to get access. The two inside the truck are under the bottom plastic kick panel above the brake. You have to remove the 3 small phillips screws holding the black kick panel to the underside of the dash. Then remove the 2 - 7/16 hex head bolts holding the hood release and the door strap to the body. Gently pull the panel down about 8". The steering column goes straight in and takes a hard right turn through the firewall. Reach down and feel along the shaft for the 2 grease fittings. You may need to turn the steering wheel to expose them.
Whenever I change my oil I check all the fluids under the hood, the transfer case, geared hubs and the differentials. I go through the truck from top to bottom and look for wet spots that could indicate leaking seals. I also snug up hose clamps and oil the door locks and brush guard release pins.