The SN95 chassis was one of the Mustang’s longest-lasting generations. Towards the end, in 2004 there were very few recalls, and almost all had to do with aftermarket lamps. Owners consider the 4.6-liter engine as one of the most reliable engines Ford has ever built, though they weren’t without problems. That said, there are some preventative maintenance owners can do to elongate their Mustang GT’s life. Most of it is simple and cheap, while some of it may require a couple of jack stands and some elbow grease. Staying on top of this maintenance can ensure a 4.6-liter will last to 300,000 miles.

Change the PCV valve every 30,000 miles

A common point of maintenance with the 4.6-liter is its positive crankcase ventilation (PCV) valve. An engine’s crankcase produces gasses from burned fuel, so the PCV valve reroutes those gasses back into the combustion chambers. Before the PCV valve, those gasses were routed to the exhaust. The PCV valve is part of an engine’s emissions equipment. Prices can range from $10 for an aftermarket one or $50 for an OEM Motorcraft part. It can be found screwed into the passenger side valve cover with a hose attached. 

Transmission fluid should be looked at every 30,000 miles

Owners recommend changing fluids every 30,000 miles or so. This includes flushing the radiator and replacing the gear oil in both the rear end and the transmission. Luckily Ford made all of this relatively easy to do. Removing the gearshift makes replacing the transmission fluid much easier, as it can be filled from the top instead of with a pump underneath the car. There’s a drain plug that’s easily accessible on the underbelly of the transmission. 

Differential oil needs some attention 

Differential gear oil is a little more complicated, but not much more difficult. Remove all bolts holding the differential cover except the top one, pry the cover away from the differential and allow all the fluid to drain out through the gap at the bottom. After the fluid drains, remove the cover entirely and clean everything with brake cleaner. 

Scrub the cover gasket mating surfaces thoroughly, and replace the cover with a new gasket. Looking straight on at the differential cover, the filler plug sits at the top left, where the axle housing meets the differential. Pump fluid in until it starts to come out, and then plug it back in. The Mustang uses an 8.8-inch differential, and all 8.8s take two quarts of ATF.

Keep up with basic checkups

SN95 New Edge Mustangs have a recommended regimen of preventative maintenance which should happen fairly often. Owners should check their exhaust, heat shielding, the cooling system, the braking system, and non-sealed steering linkages every 15,000 miles. At a certain mileage, owners should check serpentine belts and the cabin air filter as well. It takes some time to check all of these things independently, but a trained mechanic can inspect all of these parts in about an hour. As long as the car is cared for, it can last forever.