Fill your Toploader with any quality 80W-90 GL-4 gear lubricant until the oil level reaches the fill plug opening. It should take approx. 2 quarts. We recommend changing the gear lube for the first time between 500 and 1000 miles to remove the grease used to pack the needle bearings that has dissolved, Permatex, break in metal, glass beads etc. We use several new parts in our transmissions and they will seat in with each other during the break in period. It is not uncommon to see very fine metal on the magnetic drain plug when you drain the oil the first time.


We recommend changing the gear lube every 20-25,000 miles in normal street driving applications. If you have higher than stock horsepower or drive your car aggressively you should change the gear lube every 10-15,000 miles. We recommend Brad Penn 80W-90 GL-4 gear oil.


Toploaders used in racing applications need a break in period. Put some EASY laps on the transmission at low to mid rpm lightly accelerating and decelerating in each gear. This will give the gears a chance to break in and dissolve the grease in the needle bearings used during assembly. After a few laps, drain the transmission and clean the magnetic drain plug, then fill with 2 quarts of high quality GL-4 gear lubricant. Once completed, the transmission should be race ready. We recommend Brad Penn 80W-90 GL-4 gear oil.


Synthetic oil is very popular in the automotive industry today. The way a Toploader is designed it needs a certain amount of friction for the blocker rings to synchronize shifts. We have had people try synthetics and say it works great and some say it doesn't work at all. Everyone agrees that standard gear lubricant does work. The biggest determining factor as to whether it will work or not is the driver. If you drive your car normally and shift it normally synthetic would be a great choice. If you drive aggressively or want to shift fast then synthetic may not work well. If you try synthetic gear lube and it does not work for your driving style drain the transmission and try standard 80W-90 GL-4 gear lubricant.


GL-5 gear lubricant should not be used in a 4 speed Toploader due to the extreme pressure additives that are aggressive to the soft metals.

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