Mobil1 Synthetic Fluids
I recall when Scott Brady drove the Expedition West 2004 Toyota Tacoma up to the Arctic Ocean & back to Arizona on just one fill of Mobil1 synthetic engine oil. Upon returning from the 9,000 miles of harsh winter driving, those fluids were drained & analyzed, and still had plenty of life left in them.
Since I just hit 100,000 miles on my Tacoma prior to departure on this trans-continental drive, I decided it would be a good idea to switch over all my fluids to Mobil1 synthetics. After a quick trip to AutoZone, I came back with quite a few quarts of the good stuff. Not only would I fill up the engine oil with it, but also the automatic transmission & differentials.
A fine lineup
With a 75,000 mile warranty & since I had not yet had a single mechanical or computer failure, I had always taken it to a mechanic for the regularly scheduled oil changes & services. So this would be the first time I changed any fluids myself. To date, I had only wrenched on my truck to install the aftermarket suspension components, ARB Bull Bar, & other minor modifications. I consulted the factory service manual as well as several online resources (tranny, diffs). Much of this learning curve was frustrating, since taking it to a mechanic would have saved me many hours.
I’m glad I did this in Prescott before departing, as I found some issues with shoddy work from previous mechanics. It appeared that incorrect wrench sizes were used on both the front & rear differentials for the drain & fill plugs. The rear uses standard 24 mm bolt heads, and the edges of both were a little chewed up. They were also torqued well beyond the recommended 36 ft-lbs. Even worse, the front diffs are a 10 mm hex head, and it looks like a previous mechanic had used a 3/8” Allen key (which is slightly smaller). I was barely able to remove the upper fill plug. But since apparently the West Texas Arm-wrestling Champ had over torqued & stripped out the drain plug, I was unable to crack loose the bolt (even with a breaker bar). My buddy Clark even tried to help out with an easy out tool, but that broke off too! Solution: hand pump out the front diff fluid through the fill hole, and then fill it back up with synthetics. I also made sure to purchase a replacement fill bolt before doing this. I guess at some point in the distant future I can address removing the stuck drain plug if it becomes a necessity.
Front diff: drain plug & upper fill bolt, both chewed up from the wrong size wrench
Changing the transmission fluid was the most time consuming. In order to do it right, I dropped the entire pan & removed the metal filter for cleaning. Removing the 19 bolts on the pan was fun. Then, I mistakenly used water when cleaning the metal filter housing, potentially ruining any filter element on the inside. Thankfully the local auto parts store had a replacement in stock. After cleaning off the pink residue from the stock Ready-Seal, I laid on some black RTV along with a new rubber seal. At least now I won’t have to worry about the transmission for another 100,000 miles or so.
Removing the previous seal residue before replacing the pan
Sweet & Sour sauce? Nope. Synthetic ATF.
The engine oil was pretty straightforward. I had already switched over to synthetics about 20,000 miles ago, so wasn’t too worried about doing a full flush on the system. I even used a premium Mobil1 oil filter (which I’ll be taking a spare along with me for the trip). I hope to not have to change the oil on the trip, but will swap out the filter about halfway through.
