Looking through the service records for my 4runner, I found this:


It looks like when they did the diff and transfer case service they just opened it up and added some BG Multi Gear Concentrate. If they replaced the gear oil it would show up as a part, right? Bulk oil shows up under the oil changes.

When I asked the service writer about it, he told me "that's good stuff". He wouldn't elaborate on whether they changed the gear oil, but I was frustrated with the whole trip to the dealer, so I didn't push it. I later learned that they get kickbacks from BG to sell this stuff to consumers.

BG MGC seems to come in a 6oz bottle. Here's the MSDS:
http://www.lubri-care.com/msds/downloads/325.pdf
The ingredients look like lubricating stuff. A chemical similar to OLEYLAMINE is found in Amsoil Slip Lock Gear Oil Additive (friction modifier/limited slip additive), and Phosphoric acid esters are also found in Mobil 1 gear oil, and it may be an extreme pressure additive.

The crush washers match the parts in Changing Differential & Transfer Case Fluids - Pics Included except the transfer case number, which is different.

I'm trying to figure out if the gear oil was ever changed, or if it would be a waste to do it soon? I'm at 82,000 miles now, and this service was done at 61,000 miles. If they really changed it, it isn't be that old. MGC doesn't look inherently bad, but if it was good wouldn't oil manufacturers include that stuff from the factory? I'm leaning towards just changing it all since I don't know what's in there, and I will probably never have to do it again.

A similar service was done at 35,000 miles, but only one gasket was used for each. That strongly suggests they didn't drain it and refill.

Stories like this are precisely why I choose to do this maintenance myself, along with the fact that one can save a boat load of $$$ over what the dealer or just about any shop charges. Of course, not every owner can do it themselves. They may not have a garage or the right tools, or maybe they live in a complex that bans all vehicle maintenance, or they just don't want to handle smelly gear oil, or a whole list of other valid reasons. There are some shops (not dealers) that have large windows where you can watch them do the work. Armed with the owner's manual, one can tell the shop which weight gear oil to use in each differential (my '08: front & xfer take 75W-90; rear takes 80W-90), and then sign on to My Toyota and key in each service entry to keep their T4R records up to date.

depends how the parts guys bill it out and if they bill it to service or bill it to the tag. It also depends how that dealership bills out their oils, some dont bill on the tags for shop oil. Only if they get it out of parts stock. It very well could be they didnt change the fluid and just added their kick back concentrate. But it could also just have been billed differently.

And all service writers get kickbacks, so do most techs. Dealerships dont screw people, negligent people screw themselves. Its a business remember.

Probably explains why it cost $105 to have the rear diff fluid changed and another $105 to have the front diff changed the first time I had the service done. Both were done at the same time. I was able to watch the tech. He unscrewed the fill and drain plugs, drained out the old gear oil, put the drain plugs back in, filled both diffs with bulk oil using the same long hose connected to a pump, put the fill plugs back in, and tightened them using a good amount of his 200+ lb body weight. I could see him reusing the crush washer on the rear diff (I didn't know better to say anything at the time). Both diffs done in 20 mins.

Takes me an hour since I don't have a lift or fancy pump, but it feels good saving a bunch of cash. Oh, and I fill with gear oil of the correct viscosity (slightly different between frt and rr), install new crush washers with a coating of anti-seize, and torque the fill and drain plugs according to factory specs.

Just sayin'. This is one of those service items where doing it yourself is not that difficult and really worthwhile.

And it smells awesome....

To clarify, the previous owner had this done. I took it to the dealer once for a free oil change when I bought it, but from now on I do everything myself.

I was hoping I could figure out for sure if the fluid was changed, but it sounds like the way it's billed is inconsistent, so this might be a normal service or a "special" service that just adds the magic additive without changing the fluid. It seems like a waste to change it again after just 20-30,000 miles if the oil was changed, but I don't know what's in there and I'll probably never have to do it again.

For every job I've done so far, the tools needed have been cheaper than having it done. The difference is that I can use the tools again in the future.

I'm going to use Mobil 1 75W-90 all around. The front and rear for the V8 call for 80W-90 (or 90W which no longer exists), but 75W-90 shouldn't hurt, and it should improve fuel economy in cold weather. For the V6 the front calls for 75W-90 and the rear calls for 80W-90. The transfer case always wants 75W-90. I have no idea why there would be these subtle differences.

I planned to do the same. I really should get mine changed soon.
USUALLY its one of the first things I do when I purchase a vehicle. change all the fluids, regardless. so I know its been done.

other than oil changes, I haven't touched this one yet...

I'm slowly working on all the fluids.

The dealer did the oil free when I bought it (previous owner bought a 3 pack but only used two). I did the power steering fluid and brake fluid recently. I'll do the oil again soon, and probably the gear oil. I went through lots of washer fluid this winter, so that's nice and fresh! I'll probably do the coolant this fall when I do the timing belt, water pump, and add a block heater. That just leaves the transmission fluid, I think. Oh, and grease the driveshafts. The clunking is coming back after a few thousand miles, so I need to do that again.