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My question was does anyone use synthetic 15W40 in their DMAX 7800? Can the new Topkicks and Kodiaks with the DMAX 7800 use synthetics? My WT5500 has a DMAX 7800 & the owners manual tells me "Do Not Use Synthetic Oils". This engine is probably a little different than the Dmax 7800s going into the new topkicks (6500-8500) since my truck was completely made in Japan (except for the van body). I do my own maintenance and this question had always bugged me. I like the quicker cold starts with synthetics and extended drain intervals with synthetics. What design makes this engine uncompatible with synthetics?
heres some more history on my truck and some pics:
Bought this 02 GMC WT5500 new in May of 03. Was originally interested in the Topkick but sales pointed me toward this truck. Overall, I am very happy with this truck. I like the larger cab and cabover design (great for tight city streets). The cab is exactly the same as my other larger GMC T8500 tandem truck except for the seats. The only problem I've had was a starter relay failing causing the truck not to start but I was able to get the truck running again by manually wiring 12V direct to the starter (did this for 2 weeks until I got it fixed).
It has a DURAMAX 7800 7.8L IL6, 200HP @ 2400 RPM, 441 lb/ft @ 1500 RPM
The trans. is an ISUZU 6 Spd. OD manual (MLD6Q)
Truck is extremely fast, even though the max spd. on the speedo was 85, it can and usually does go past it (around 88-90 MAX) with minimal pedal effort. This is the first Medium Duty that I feel has enough power!
heres some more history on my truck and some pics:
Bought this 02 GMC WT5500 new in May of 03. Was originally interested in the Topkick but sales pointed me toward this truck. Overall, I am very happy with this truck. I like the larger cab and cabover design (great for tight city streets). The cab is exactly the same as my other larger GMC T8500 tandem truck except for the seats. The only problem I've had was a starter relay failing causing the truck not to start but I was able to get the truck running again by manually wiring 12V direct to the starter (did this for 2 weeks until I got it fixed).
It has a DURAMAX 7800 7.8L IL6, 200HP @ 2400 RPM, 441 lb/ft @ 1500 RPM
The trans. is an ISUZU 6 Spd. OD manual (MLD6Q)
Truck is extremely fast, even though the max spd. on the speedo was 85, it can and usually does go past it (around 88-90 MAX) with minimal pedal effort. This is the first Medium Duty that I feel has enough power!
