Sorry to say I have never heard of tanning a deer skin with Diesel, I suspect it would work but if you want to tann a deer skin, borax and alum is also not tanning, that is curing.
To tan a deer skin properly you need to go through several stages, and different tans give different results. For instance most rugs for floors, similar to sheep skin rugs, are Chrome Tanned, this shrinks the pelt slightly giving a denser feel and the distinctive blue grey colour sometimes on the back. This tan is useless for Taxidermy purposes.
1. Remove all fat, meat and sinew from the skin.
2. Wash the skin thouroughly in warm water with biological washing powder. This will release all the blood and dirt from the skin and also some of the grease.
3. Rinse in cold water and drain.
4. For every 3lbs of dry skin weight, mix 7galls of warm water, with 6lbs of salt, and 7.5oz of Formic Acid. (note wear gloves and goggles be careful) make sure its in a plastic dustbin or container, dont use metal.
Punch the skin into the solution and make sure you have all the air pockets out, otherwise bacteria will live in the air pocket and the skin may slip. Leave in the solution for two or three days. You will notice it turns the flesh white.
5. Take out of solution and drain, once drained you can thin the skin down on a machine or by hand with a knife, as you will find the fixing of the skin has plumped up the pelt. You can return it back to the solution as much as you like but ensure the acidity does not drop otherwise the skin may slip.
6. Buy yourself some Lutan FN tanning powder, or a Ktan tanning kit. I use Lutan FN, and after fixing the skin I then mix 7galls of warm water, 3lbs of salt, 40z of Bicarb, and about 7oz of Tanning oil, plus 12oz of Lutan FN Tanning Powder. Mix it up and drop the skin back in and punch it into the mix to release any air pockets. Go back every 15 minutes for the next hour and stir and punch the skin into the solution with a large stick. Leave for about 2 days.
7. Take out and drain, and dry by stetching out the pelt, when it is damp mix up some Tanning Oil with warm water 60/40 and paint onto the skin, and let it dry. When the skin is dried you will be able to stake it over a wooden pole.
8. Staking measn breaking the fibres up, and as you work the skin on the flesh side you will notice that it breaks down into a fluffy texture and soft. You have tanned your skin!!
Any other method with just salt, borax (which makes the skin hard) is curing not tanning, the skin will rot if it gets wet over a period of time. And it will not be soft and supple.
Good luck.