slick
New member
- Sep 18, 2026
- 4
- 0
Hello, everyone!
I wanted to give everyone an update on my new GMC Sierra and share a few things I've run into since installing my Titan 43-gallon replacement fuel tank.
1. Titan 43-Gallon Replacement Tank and Warranty Concerns
First, I absolutely love the Titan 43-gallon replacement tank! So far, zero leaks, and my local diesel garage did an excellent job with the installation. I purchased a scratch and dent tank for about $300 less, and I was told by the salesman it may be an off color, but the tank is under warranty.
The dealership wanted nothing to do with installing the aftermarket tank. However, I am concerned about a possible warranty issue down the road. The dealership's service manager told me that installing the tank could potentially void my warranty. I purchased an additional six-year warranty through the dealership, and I certainly don't want to lose that coverage.
My understanding is that under the federal Magnuson-Moss Warranty Act, installing an aftermarket replacement part does not automatically void an entire vehicle warranty. A manufacturer or warranty provider generally must have a valid reason to deny a claim, such as demonstrating that the aftermarket part caused the failure.
I'm not looking for a fight, but if the dealership tries to deny a legitimate warranty claim simply because I installed an aftermarket fuel tank, I may have to stand my ground!
I previously had a 40-gallon replacement tank in my F-150 for seven years without any problems.
Has anyone else run into warranty issues after installing an aftermarket Titan fuel tank?
2. Fuel Gauge and Computer Programming
Here is another question.
My truck's computer still seems to be operating based on the original factory fuel tank capacity. I'm not sure whether the ECM or BCM needs to be reprogrammed or whether there is another way to calibrate the fuel level readings.
After the installation, I filled the new Titan tank completely.
I drove approximately 640 miles, and my fuel gauge was showing just under half a tank. The computer was estimating that I had approximately 250 miles of range remaining.
I stopped and put in 23 gallons of diesel. After filling the tank, my displayed range returned to approximately 640 miles.
Obviously, something doesn't seem quite right with the fuel-level and range calculations.
I'd like to know if anyone has experience getting the fuel capacity or fuel-level readings recalibrated to work properly with the larger tank.
The dealership has already indicated that it won't handle this programming. Does anyone know of a diesel shop or someone with the proper GM diagnostic equipment who can make this adjustment?
I'd appreciate any recommendations.
3. Diesel Fuel Additives – Is the Dealership Right?
I also asked the dealership's service manager what fuel additives he recommends for my new GMC Sierra Duramax.
His answer was simple: USE NOTHING!
Could that really be the best advice?
On my previous F-150, I used two Stanadyne products:
Stanadyne Performance Formula
Stanadyne Lubricity Formula
I used them consistently from my first fill-up until I traded the truck in.
I purchased the half-gallon bottles, which lasted approximately a year. I always used a measuring cup and funnel to get the dosage right.
My routine was to add approximately 4–5 ounces of Performance Formula and additional Lubricity Formula at each fill-up.
My previous truck had a 40-gallon tank, and I rarely allowed the fuel level to drop below one-quarter tank.
My understanding is that Stanadyne Performance Formula already contains lubricity-enhancing ingredients, along with other benefits such as cetane improvement and water management. The separate Lubricity Formula provides additional lubricity.
I've also read that using Performance Formula alone at the manufacturer's recommended dosage may be sufficient, without adding the separate Lubricity Formula.
I would like to hear from other Duramax owners who have experience with these products.
A few questions:
Do you use Stanadyne Performance Formula in your GMC Duramax?
Do you also use the separate Lubricity Formula, or is Performance Formula enough?
Do you follow the dealership's advice and use no additives whatsoever?
Have you had any problems with additives and your emissions equipment, DPF, or fuel injection system?
I'm interested in hearing real-world experiences, not just what someone read on the internet.
4. One Last Thing – Fuel Prices!
One of the reasons I wanted the larger tank was to give myself more flexibility when traveling.
I recently paid $5.99 per gallon of diesel in Pennsylvania, and I was seeing prices as high as $6.85 elsewhere by using gas buddy. .
Having a larger fuel capacity gives me the opportunity to plan my fuel stops and shop around for better prices rather than having to stop wherever I happen to be running low.
That's exactly why I wanted the 43-gallon Titan tank! I do not want to stop for fuel every week.
I wanted to give everyone an update on my new GMC Sierra and share a few things I've run into since installing my Titan 43-gallon replacement fuel tank.
1. Titan 43-Gallon Replacement Tank and Warranty Concerns
First, I absolutely love the Titan 43-gallon replacement tank! So far, zero leaks, and my local diesel garage did an excellent job with the installation. I purchased a scratch and dent tank for about $300 less, and I was told by the salesman it may be an off color, but the tank is under warranty.
The dealership wanted nothing to do with installing the aftermarket tank. However, I am concerned about a possible warranty issue down the road. The dealership's service manager told me that installing the tank could potentially void my warranty. I purchased an additional six-year warranty through the dealership, and I certainly don't want to lose that coverage.
My understanding is that under the federal Magnuson-Moss Warranty Act, installing an aftermarket replacement part does not automatically void an entire vehicle warranty. A manufacturer or warranty provider generally must have a valid reason to deny a claim, such as demonstrating that the aftermarket part caused the failure.
I'm not looking for a fight, but if the dealership tries to deny a legitimate warranty claim simply because I installed an aftermarket fuel tank, I may have to stand my ground!
I previously had a 40-gallon replacement tank in my F-150 for seven years without any problems.
Has anyone else run into warranty issues after installing an aftermarket Titan fuel tank?
2. Fuel Gauge and Computer Programming
Here is another question.
My truck's computer still seems to be operating based on the original factory fuel tank capacity. I'm not sure whether the ECM or BCM needs to be reprogrammed or whether there is another way to calibrate the fuel level readings.
After the installation, I filled the new Titan tank completely.
I drove approximately 640 miles, and my fuel gauge was showing just under half a tank. The computer was estimating that I had approximately 250 miles of range remaining.
I stopped and put in 23 gallons of diesel. After filling the tank, my displayed range returned to approximately 640 miles.
Obviously, something doesn't seem quite right with the fuel-level and range calculations.
I'd like to know if anyone has experience getting the fuel capacity or fuel-level readings recalibrated to work properly with the larger tank.
The dealership has already indicated that it won't handle this programming. Does anyone know of a diesel shop or someone with the proper GM diagnostic equipment who can make this adjustment?
I'd appreciate any recommendations.
3. Diesel Fuel Additives – Is the Dealership Right?
I also asked the dealership's service manager what fuel additives he recommends for my new GMC Sierra Duramax.
His answer was simple: USE NOTHING!
Could that really be the best advice?
On my previous F-150, I used two Stanadyne products:
Stanadyne Performance Formula
Stanadyne Lubricity Formula
I used them consistently from my first fill-up until I traded the truck in.
I purchased the half-gallon bottles, which lasted approximately a year. I always used a measuring cup and funnel to get the dosage right.
My routine was to add approximately 4–5 ounces of Performance Formula and additional Lubricity Formula at each fill-up.
My previous truck had a 40-gallon tank, and I rarely allowed the fuel level to drop below one-quarter tank.
My understanding is that Stanadyne Performance Formula already contains lubricity-enhancing ingredients, along with other benefits such as cetane improvement and water management. The separate Lubricity Formula provides additional lubricity.
I've also read that using Performance Formula alone at the manufacturer's recommended dosage may be sufficient, without adding the separate Lubricity Formula.
I would like to hear from other Duramax owners who have experience with these products.
A few questions:
Do you use Stanadyne Performance Formula in your GMC Duramax?
Do you also use the separate Lubricity Formula, or is Performance Formula enough?
Do you follow the dealership's advice and use no additives whatsoever?
Have you had any problems with additives and your emissions equipment, DPF, or fuel injection system?
I'm interested in hearing real-world experiences, not just what someone read on the internet.
4. One Last Thing – Fuel Prices!
One of the reasons I wanted the larger tank was to give myself more flexibility when traveling.
I recently paid $5.99 per gallon of diesel in Pennsylvania, and I was seeing prices as high as $6.85 elsewhere by using gas buddy. .
Having a larger fuel capacity gives me the opportunity to plan my fuel stops and shop around for better prices rather than having to stop wherever I happen to be running low.
That's exactly why I wanted the 43-gallon Titan tank! I do not want to stop for fuel every week.