i usually will not do a tranny flush with over 100000 miles on a vehicle. if over that many miles, have a transmission specialist inspect your vehicle.
low compression, if over 100000 miles, needs new rings
i have not found a blazer or jimmy that gets over15 mpg no matter what ya do to it.
Use the manufacture recommended weight and switch to a High Mileage oil.
5w30
That depends on how much you have to spend.
100000/4000000000 as a decimal is 0.000025.
1666/100000 = 833/50000
depends, if it has over over a 100000 miles youd probly get around $2800-$3500 depending on what shape its in
Given that you dedicated 50 years to this goal, that's 2000 miles a year. This comes out to about 5.5 miles a day over those 50 years, so while it is possible, it is not likely.
Expressed as a decimal, 88/100000 = 0.00088
Expressed as a decimal, 134/100000 = 0.00134