I thought since everyone was posting Mileage threads I would try something different. I just bought a completely stock 155K mile 1991 4x4 5-speed 22re Pickup. I drove it home from Tennessee and averaged 21 miles to the gallon with factoring for my 31 inch tires and 4.10 gears @ 65 miles per hour. After getting it home and looking it over more thoroughly I discovered that the truck has many of its original factory equipped components like plug wires, cap and rotor, O2 sensor and spark plugs. The gear lube in the differentials was no different I would venture to say that nothing maintenance wise has been done to this truck in a very long time or since it was at the factory being assembled.

At this point I realized that I had an opportunity to discover exactly how much performance and efficiency can be gained by performing a tune up and doing all the required maintenance as well as the periodic adjustments included in the factory maintenance schedule. I figure I am starting with a great test subject as my truck as never been modified in any way and still retains its factory components. I will continue this thread until all the major maintence items have been completed.

MPG calculated no maintenance performed (starting point): 21.0 MPG

Stage one tune up:
-Valvoline 10w30 oil change
-Denso Spark plugs
-Denso Plug wire set
-OEM Cap and Rotor kit
-Wheels rotated and balanced
Date completed: 12-24-2009

I plan on averaging several tanks of gas to figure out how much performance and efficiency was gained or lost by my stage one tune up under similar driving conditions as my first calculations.
Check back for my mileage postings as I will keep up with this thread and my calculations. Stay tuned for stage two which is a full synthetic gear oil change to Red-Line Synthetic oil for the front and rear axles and the transmission and transfer-case. I will include more stages as money allows. Feel free to post your thoughts and comments as well as any suggestions. Thanks

 

With all due respect, if the truck was taken, by the previous owner(s), to a dealer which performed maintenance, would it not have what would appear to be the original plug wires, cap and rotor, O2 sensor and even spark plugs since that maintenance would use OEM parts?
That being the case, your assumption is flawed.

However, I do look forward to your results.

 

The plug wires were dated 1991, and although the spark plugs don't have a date on them I'll post pictures to show my suspicions on thems being orginal or close to original. But you are most definatly correct as I cannot validate what may have been changed over the years with OEM parts. I do know that by it's current state, I am safe in assuming that nothing has been done in several years. I will post some pictures to show the original parts. Thanks for your input.

 

Just double checked everything and the spark plugs were NOT factory as they were NGK and not Denso. However, the wires, cap and rotor defiantly appear to be.
The plug wires are date coded "1991" the same year as my truck.

 

date coded is not the same as installed.

 

Very true, I see my flawed logic now. Sorry for the confusion. At any rate We'll see the results soon enough.

 

Have you factored in the speedometer being off with the 31's

 

He said he did that in his first post.

 

Have to avoid the temptation to drive differently when you're looking for results too.

 

Thanks for you input, and yes I have been using consistent numbers as far as the calculation of MPG for my 31 inch tires and I plan on keeping my speed constant throughout the duration of testing and proper tire pressure. I'm trying to eliminate as many variables as I can to see how much difference tune-up improvements make. Bear in mind that most of my driving is highway with some limited stop and go traffic. I am keeping detailed records, if you want any of my information please let me know. Thanks for looking!!

 

Im getting 22mpg around town with 31's and stock 410 gearing,but,it REALLY does make a difference on HOW you drive.
I noticed this recently before and after a tune up. How I drove made more of a positive difference.

 

Alright, after finishing three tanks of fuel at the same reasonable driving speed of about 65 MPH, on the same roads as before, I have calculated 22.7 miles per gallon including the speedometer error for the 31 inch tires and the necessary calculations to correct it. That's a pretty good improvement for just maintenance items. Next step is Redline synthetic gear oils for the drive-train. I'll check back in with more information as it becomes available.

Beginning: 21.0 at best @ 65MPH

Stage one maintance items: 22.7 after three tanks average @ 65 MPH

*I realize there are some factors that make this not exactly scientific, but I have noticed a definite improvement in over all performance and driveability. So I figure I'm not doing too bad for a shade tree mechanic.

 

Our fuel is oxygenated as well but they do not make the switch to regular fuel until late march. I'm hoping to have mos of the maintenance done by then. But I have hit a snag as I just noticed I have a head gasket leaking coolant down the side of my engine. So I ordered all my parts and I'll get back on track as soon as I'm finished with the repairs.