$2700 for a rear main seal and clutch?

[Hib Halverson]

If we are talking about an automatic trans, "flush" means replace all the fluid with new fluid using a machine which connects to the trans and sucks out the old fluid and pumps in new fluid. "Change" draining the fluid in the trans pan and refilling the trans. Fluid inside the converter or in the passages inside the trans doesn't get changed.

For a manual the terms are interchangeable.

"Drive axle lubricant" = rear end oil = differential fluid

GM does not usually list a change interval with manuals, but I recommend 3yr/36,000.

Also you said

 

[Hib Halverson]

The Owner's Manual probably did not recommend use of differential fluid in the automatic trans or the manual transmission.

With respect to an automatic trans, "flush" means replacement of old fluid with new fluid. Typically this is done with a service tool which connects to the transmission and sucks out old fluid and replaces it with new. "Change" usually means draining the fluid in the trans pan and refiling it.

With respect to a manual trans "flush" and "change" are synomous.

"drive axle lubricant" = "rear end oil" = "differential fluid"

in most cases of passenger cars, GM does not recommend transmission lubricant changes, however, I feel transmission durability is enhanced by doing that every 3yrs/36,000 miles.