My son bought an '89 Ford Probe last year. It has 94,000 miles and a 5 speed manual transmission. We don't know if the transmission fluid has ever been changed or if it even needs to be. I've called several Ford dealers in the area and they can't give me a definite yes or no. Will you please give me your opinion and any suggestions for maintaining this vehicle at least for the next four years?
Did you know that your 5-speed manual transmission uses automatic transmission fluid? The reason behind using a lighter weight fluid is the ease of shifting during extremely cold temperatures. In the old days you would get in your car on a cold winter morning, and it would take two hands to get your 4-speed into first gear. The problem was the 90w gear oil they were using at the time, which becomes thick as molasses below freezing.
As for the question about servicing your transmission, Ford, along with several other manufacturers, does not specify a time or mileage to replace manual transmission fluid as part of the maintenance schedule. A simple way to determine if the fluid warrants replacement is to look, touch and smell. If it looks black, feels gritty or smells burnt, then it's time. It's an inexpensive service that requires little labor and only a few quarts of fluid. When in doubt, change it.
As far as your son's Probe is concerned, nearing the 100k mark on the odometer and no record of previous maintenance, I suggest giving it the once-over. If it's got the four cylinder engine, have your mechanic check the condition of the timing belt. It should have been replaced at 60,000 miles. Get a safety inspection of the brakes, tires, steering, suspension, lights, mirrors and horn. Check and/or service the coolant system, belts, hoses and battery. Go over the tune up status (including ignition wires). Also be sure there are no serious leaks at the engine or transmission.
When you get the estimate on the work, sit down and compare what the car is worth and what you are about to invest. You really want to be money smart in this situation.