I am a proud new Dodge Cummins owner and am trying to get in the swing of things with this truck. I noticed that my transmission gear oil is a little low (5-spd NV4500). I was going to just change it and put some fresh stuff in there until I priced it at the dealer. $27. 95 per quart!!! I have found some synthetic gear oil from Castrol (75W90) that is $7. 59 per quart, big difference. The question is, this particular oil conforms to the API GL-5 standard and not GL-4 which is called for in the owner's manual. Is this ok to use or is there something else that would be better. Also, I noticed that there is not a drain plug on the bottom of the transmission. Do you have to just take the PTO plate off to drain the thing? Any help will be greatly appreciated. Please excuse my ignorance, I know I'm a newbie.
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