Fluid flush/filters

[whoudi]

Good afternoon fellas.

Was doing the yearly oil change on my 87 Grand National and noticed some oil seepage from the oil pan gasket. I'm taking it into my mechanic to check out later this month and thought now would be good time to change all of the fluids and filters. I have a nearly-stock 52,xxx mile GN. In my 10 years and 25,000 miles of ownership I have addressed basic maintenance issues when they arise. I did have to do head gaskets 6-7 years ago. It has a street TurboTweak chip, replaced the powermaster unit with vacuum driven system, and new coil ignition module off the top of my head in the past few years. This thing has been a great, fun reliable car for me and I want to keep on the road another 50 years.

I already have some RDI-25 additive ordered for the coolant. What fluids would you recommend for the diff and trans? I'm assuming basic power steering fluid would work fine? Any recommendations would be great. Thanks.

 

[1986 Buick GX1]

I like everything synthetic.

Mobil 1 makes a 75- 140 LS synthetic gear oil that’s for the G80 Limited Slip diff. Not LS as in chebby.

Synthetic DOT 5 brake fluid is ok as it absorbs moisture. However silicone DOT 5 doesn’t and will trap moisture between the fluid and the steel line causing rust on the inside of the line, or so it’s reported.

Dextron VI trans fluid is available in synthetic as well and is backwards compatible except for the Allison trans.

Synthetic power steering fluid is available too. Valvoline has it as well as others I’m sure.

The best part is Mobile 1 is making synthetic blinker fluid now too.
Now we can go 100% synthetic. Lol