Frequently Asked Questions About Peterbilt 386 Diesel Fuel Tanks

What size fuel tanks are available for my Peterbilt 386, and how do I know which will fit?

Peterbilt 386 trucks typically accommodate fuel tanks ranging from 50 to 150 gallons, with the most common sizes being 100, 120, and 150 gallons. The correct size depends on your truck's wheelbase and frame rail spacing. For 2006-2015 Peterbilt 386 models, measure from the back of the cab to the rear suspension to determine maximum tank length. Standard diameter tanks are 23 or 25 inches. Always verify your frame rail width before ordering - most 386 models have either 34.5" or 40" spacing between rails.

Are aluminum or steel fuel tanks better for my Peterbilt 386?

Aluminum tanks are the most popular choice for Peterbilt 386 trucks due to their corrosion resistance and weight savings - typically 65% lighter than steel equivalents. A 120-gallon aluminum tank weighs approximately 85 pounds empty versus 240 pounds for steel. However, steel tanks cost 30-40% less and offer better impact resistance for severe-duty applications. If you operate in areas with heavy road salt or coastal environments, aluminum is strongly recommended despite the higher initial cost.

Can I install a larger fuel tank myself, or do I need professional installation?

While experienced mechanics can install Peterbilt 386 fuel tanks, professional installation is recommended due to DOT regulations and safety requirements. Installation requires proper tank straps (typically included), mounting brackets specific to your frame width, fuel line connections, and proper venting. The process takes 3-5 hours and requires lifting equipment. Critical steps include ensuring proper ground clearance (minimum 14 inches), secure mounting with grade 8 bolts, and leak testing all connections. Many customers report fuel gauge calibration as the most challenging DIY aspect.

Will aftermarket fuel tanks void my Peterbilt warranty or affect resale value?

Installing quality aftermarket fuel tanks that meet DOT specifications will not void your Peterbilt powertrain warranty. However, any damage caused by improper installation or non-compliant tanks may not be covered. For trucks under warranty, document the installation with photos and keep all receipts. Regarding resale value, properly installed aluminum tanks from reputable manufacturers typically maintain or increase value, especially when upgrading from smaller OEM tanks. Ensure any tank you purchase has DOT certification markings.

What's the difference between D-style and cylindrical fuel tanks for the 386?

D-style (also called D-shaped) tanks mount flush against the frame rail with a flat back, maximizing fuel capacity while maintaining ground clearance. They're ideal for Peterbilt 386 models with limited frame space. Cylindrical tanks are completely round and typically easier to install but may reduce ground clearance by 1-2 inches compared to D-style. For 386 tractors with sleeper cabs, D-style tanks often provide 10-15% more capacity in the same space. Cylindrical tanks generally cost 15-20% less and have wider strap compatibility.