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Where to start with used truck upgrades

I am buying a used truck. It is a 2005 freightliner century with 732,000 miles. Detroit series 60, Eaton 10 speed, 358 gears, mismatched 22.5 tires. I pull a 53' reefer. I am looking for guidance as to where to start with upgrades to increase fuel mileage. Starting with little money. Truck needs to pay for upgrades as I go.

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Drive slow. I would say fleet-air filter. I saw 4/10's instantly.

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First upgrade for me would be a flow through muffler. Very cheap. Pittsburgh power sells one for $158.

Now remember you need to make sure the truck is in good mechanical condition. Make sure to run the overhead and check the charge air cooler. Be there when they do the charge air cooler test so you can see the psi loss. If they do the test and just tell you that its within spec you could loose 5 psi in 15 second and that would cost you a lot in fuel mileage. Some people will tell you 1 or 2 lbs in 15 seconds is ok but for me personally I don't like any loss.

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Hi Jackie, am getting a charge air cooler installed today, if there is psi loss what do they need to do so that there is none? Thanks :)


Hi Kathy if the shop find a pressure loss they will be able to find out where they are. They can check the boots, clamps, intake manifold gaskets, and finally the charge air cooler.


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1. Start by driving slow (60 mph or less) with more conservative driving habits.

2. Use fuel money saved to reinvest in mechanical fuel saving products.

3. Free flowing muffler like the Walker Megaflow I use for around $100 or even the PP one already mentioned.

4. Fleet Air Filter for underhood aerotruck for $299.

5. Synthetic Motor Oil. I use 5W40 Mobil One.

6. MicroBlue wheel bearings.

7. Microblue tranny.

8. Microblue rears.

9. Pittsburgh Power Exhaust Manifold and larger turbo.

10. Michelin X-One XDA Energy Super Singles drives.

11. Airtabs

12. Real Wheel Wheel covers.

13. ECM reprogramming to get rid of Nox programming in favor of fuel mileage programming.

14. Optional Pittsburgh Power Box if you want more power when needed and used wisely to gain fuel mileage.

If you have the money, go ahead and make the investment to jump up 2 to 3 mpg improvement or you can do a step by step improvement by re-investing the fuel savings money into the truck that eventually before you know your margin is alot larger than the days of the poor fuel mileage truck.

You will also find yourself able to take more time off with more money to spend on your personal life due to saving fuel money.

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Hi Jackie, i had freightliner do a air leak test on the CAC, said it was leaking 1/2 psi, is that acceptable or will it make a difference in mpg's? Im currently getting 8.5 empty and 7.7 with a 38k lb load. Ive only been running this truck a week but thats what Im getting from it so far. have a C15 cat engine.

Im going to try and slowly do all the suggestions you all recommend, you all are great and very helpful

Thanks so much!


Hi Kathy, is that 1/2 PSI in 15 seconds? If so then it's nothing to worry about. Sounds like your MPG's are good so far. Keep up the good work.


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What exactly is a Fleet air filter? Is this a brand name or different type of air filter altogether?



Is there a book that I can buy that contains all of the currently accepted

best practices Kevin and you other experienced drivers talk about? I try to listen on radio, and read web sites, and talk to drivers, but it seems I end up getting pieces of the picture, and not the whole picture. Worse still, I get totally wrong information sometimes, and then I really don't know who to listen to and trust.

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Fleet is a brand name of a washable air filter.


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first make sure your truck is mechanically sound.

start with the cheap with upgrades.

Airtabs $220

Turbo 3000d $350

MD Alignment $375

Fleet air filter $400

OPS-eco pur $650

Let the cheap stuff pay for the bigger stuff like tires. I would do tires after those 5 things. Plus add dynamic wheel balancers and tru-balance at the same time.

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Make sure the engine is mechanically sound. It looks like you are already doing that and have replaced the Charge Air Cooler, which will help improve fuel economy. Then:

1. Slow down. This is the only fuel mileage upgrade that is ABSOLUTELY FREE and totally controlled by the driver. By letting your foot up on the accelerator, you will improve your fuel mileage and prolong the life of your engine. In particular, find your engine's sweet spot (which is usually between 58 and 63 MPH) and stay there as much as possible. Some trucks have it below 55 MPH (hence the 54 MPH club that Kevin frequently mentions), most have it just slightly above.

2. Replace the stock muffler with a performance muffler. Stock mufflers are made by Donaldson (the same guys that make the paper air filters), corrode easily, lose performance gains over time, and plug up with soot. I would suggest a Pittsburgh Power muffler instead. The $150 price tag is nothing compared to the improved performance, noise control and fuel economy.

3. Get air tabs. These will make the truck more aerodynamic by redirecting air flow. While you're at it, check all your extenders, skirts and fairings for damage and fix those when you get the air tabs on order.

4. Replace the mis-matched, recapped tires. Get yourself a set of Michelin XDA Energy tires, or if you're going to wide singles, get the Michelin X ONE XDA Energy. You'll gain fuel economy, improve your traction and make your truck safer.

5. Replace the stock Donaldson paper air filter with a Fleet Air Filter or a K&N HD Air Filter. The Fleet Air and K&N products improve air flow, are easier to service, and are lifetime air filters... They'll go hundreds of thousands of miles before needing replacement, your engine will breathe better and you'll get better fuel economy.

6. Turbo 3000D and/or FASS System.

7. OPS and Synthetic oil (Amsoil, Mobil One (also known as Mobil 1), Shell Rotella T5 or equivalent) IF the engine has no oil leaks.

There are some 60+ ways to improve fuel economy in addition to what I just mentioned. Let cheaper stuff (slowing down) pay for bigger stuff (tires).

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1. Scan Gauge (As per KR recommendation)

2. Tires

-I recommend Yokohama RY617 for Steers (RR 98) and TY517MCS (RR 102). Michelins have a slightly lower RR but the difference will not be measurable and will not make up the cost difference over the life of the tire. Anything with a low RR will be an improvement over the mis-matched set you have now.

3. OPS and Synthetic Oil

-You may not see a lot of MPG improvement but you will have a fast ROI on oil changes alone.

4. PP muffler

5. Fleet Air Filter

This is the order I would do it in for the best and fastest ROI. There are always more ways to improve, but these are the "low hanging fruit."

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Larry Rolen II will be eternally grateful.
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