I usually have my oil serviced at the dealer or an independent shop. I have a 2005 4runner with 150,000 miles.
Today I drained the rear differential for the first time. The oil that came out looked brand new (second look it was black - but had viscosity) - and I'm wondering if one of the shops didn't change it. We found all the receipts, and they told us "no".
Anyway, drain plugs (24mm) came out easy. The dealer had only one metal gasket in stock - so replaced just one.
Filled until it just started to overflow - than put drain plug back in.
