Hi everyone. I recently purchased a D8 14A8430. Doing a complete service on it for spring season. I have all of the manuals for it, but would like some input from some experienced guys. I had a 76A D6C and currently own a 4X D6D. I was wondering what everyone's thoughts were on using TDTO 50 in the transmission and final drives on the D8. In my mind, the 80W90 gear oil is fairly thick to run through the transmission filter, although I guess they ran that way for years. Just looking for opinions. Also, would like to find a useable/rebuildable starting engine for it in the future. I would need everything except the pinion and clutch lever, as everything else was removed when it was converted to direct start. Thanks

most oil companies have a smart phone app or a product selector guide on thier website. well i know caltex(chevron), mobil, bp, penrite and shell do.
if you ring their technical advice line they will also give you a recommendation. 80-90 gear lube is about the same thickness of sae 30 engine oil. note those powershift transmissions use a different oil to the manual type transmissions. the owners book and service reference have the requirements for the oil technology that was available back then.

i know chevron has changed all thier heavy equipment oil product names recently and grouped them all under the DELO banner (sidenote: the name delo means diesel engine lubricating oil and was developed originally by standard oil for caterpillar, cat actually built special single cylinder test engines for this task).

The Cat 50W TDTO is a good oil for final drives. Trans. I would use Cat 30W TDTO, better for the pumps and is designed for steering clutches.

50 wt is fine for the transmission but I would run no less than 75/140 in the final drives you need some cushion or a good film of oil especially in slow speed running, and I don’t care what CAT says they like to sell gears! I have paid the PRICE on this one on using 50 wt. in finals. 17afarmer

yes if your in hot conditions all the time definitely use a heavier oil. remember multi grade oils are the thickness of the lower number cold when cold and the higher number hot when hot. it took me a bit to wrap my head around that too. oils cheap parts are not. it might also be advantageous in those tough conditions to run a little oil stabiliser additive such as lucas or moreys basically they are a tackiness agent and make the oil stick better to the wearing surfaces. just in the final drive and bevel gear.

i know someone who ran straight moreys stabiliser in the gear drive boxes for the cutter deck on his ride on mower straight cut bevel gears get loud when a bit worn you couldn't here the exhaust(20hp v twin kohlers aint quiet) for the gear noise before treatment. he told the australian distributor about it and they started treating them with moreys at the label rate from new and found they lasted longer and ran quieter and a bit cooler too.