Fix poor fuel mileage and oil burning on GMC 2500hd with Sea Foam [SOLVED]

Great question, Hayden – there are a few things you can do with Sea Foam that could help!!

First, get a can or two of Sea Foam High Mileage and pour it in your fuel tank. Add a full can to a low tank of fuel (1/8 of a tank or so) and drive until almost empty before refueling. That will create a strong cleaning concentration of Sea Foam and give it time to work through the fuel system. If the poor fuel mileage is related to deposits/residues, Sea Foam will help! Might be a good idea to do that a couple times.

Next, High Mileage will also help with the oil burning problem if caused by varnish/carbon restrictions. Add 1 oz per quart of oil around 100-300 miles before your next oil change. You might have to do that for a few oil change cycles before you notice a difference, but the High Mileage will progressively clean away varnish and restrictions that are causing the oil burning. Here’s a helpful article with more details as well as other causes/solutions for oil burning:

https://seafoamworks.com/stop-the-smoke-cures-for-burning-oil/#:~:text=The%20buildup%20of%20heavier%20varnish,each%20oil%20and%20filter%20change.

Lastly, if the oil pressure sensor is dirty, some people have had success with High Mileage in the oil to clean it up and get it to read correctly. So adding it to your oil might help if that’s the case.

Hope that’s helpful and keep us posted about your GMC!