1999 Silverado Questions/ Problems

KMT15 · December 7, 2008

Hey guys, I dont post much. Only use the truck in the winters and need some help/ advice.

I have a 99 Z71 with 78k miles on it. I need to change the oil and was wondering what everyone else is using. I really like Mobil 1 products and would like to go full synthetic. I also want to change the front and rear diff fluid as well as the transfer case fluid. What are you guys using? When in 4hi, its pretty loud from up front so I hope the diff isnt ruined. Also when in 4hi or auto 4wd I hear a slapping type noise when the front wheels are spinning, its hard to explain and Im not real sure what it is.

Lets see, what other problems am I having? Oh yea, climate control. 1,2,3,4 do not work, only 5... And my brakes suck, the ABS light is lit off and on and today while driving on the ice the brakes seem to loose pressure if i were to hold the pedal down and lock them up. The pedal would bottom out on the floor until I let up to let it rebuild pressure. Im assuming I need the fluid changed out. I think thats about it for now, and help would be appreciated. Thanks guys

ColoradoSkiCountry · December 7, 2008

Can't help you with the brakes, but as far as fluids go, You'll do just fine with Mobil-1 Full Synthetic for motor oil, use a AC/Delco filter or better, I preferred to stick with what the manual called for with regards to the front and rear diff, as well as the transfer case. Make sure its the blue stuff for the T-Case. As for the transmission fluid, you can go 2 ways, with a Synthetic, or just whatever the manual calls for.

svensk · December 7, 2008

Get your brakes fixed ASAP that is not good. You might just need to bleed the system, but that could also be a master cylinder going bad?

The 1-4 on the climate control happens to a lot of people, it's the resistor under the passenger side dash. take the kick plate off and you should be able to repair it. It might just be the grounding.

The ABS thing...that might be due to the other brake issue, but did you ever take your truck in for the wheel sensor recall? Being your from the rust belt the wheel sensors can get corroded and cause the ABS system to malfunction or fail.

Fluids- I run AMSOIL in the transmission, front and rear diffs and engine. GM blue fluid in the t-case. If you strictly drive your truck in the winter I recommend using synthetics, they break down slower and will cut down your oil change interval especially if you sit the truck for while.