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Driving speed for gently driven older auto

My mother in law has a 1989 Ford Taurus with 47,000 miles on it. She drove it mostly around town. Now she’s selling it to friends of ours who drive a lot on the freeway.

What is the recommended procedure for breaking the engine in so that it isn’t damaged by the higher speed. I have heard, for example, that the piston rings have built up a ridge near the top of the cylinders, and that if the car is suddenly driven much faster the additional flex in the crankshaft will cause the rings to bang into the ridge and break.

I wouldn’t worry about that, the engine goes through a reasonable range of rpms even just driving around town. What I would look at first are the tires: how old are they (you can get the age from the number on the side of each tire). If anywhere near 10 years old I’d replace them. I’d also have a mechanic go over it, change the various fluids if they haven’t been changed lately, and check the brakes for wear. Finally, check thoroughly for rust if that could be an issue.

You don’t have to worry about the speed at which the new owners drive the car. The engine was broken in a LONG time ago, and nothing you do now will change it.

This is a non-issue.

I agree with the preceding responses. “Break-in” is a non-issue on a 22 year old engine.

What will be an issue is the incredible amount of sludge that has undoubtedly built up as a result of the car having been driven less than 3,000 miles a year for a couple of decades–all in local, low-speed driving.

Those friends may cease to be friends when they have an expensive mechanical problem as a result of (pick one or more):

The timing chain breaking as a result of lubrication problems
Excessive oil burning due to worn-out rings and bearings–also as a result of lubrication problems
Valve lifters that are stuck as a result of lubrication problems

Or, in other words, break down is a much more likely issue for the next owner to deal with, rather than break-in.

Personally, I would not sell this car to anyone with whom I wanted to remain friendly.

There is no issue with the engine. It is ready for highway speeds now. What might need attention is the tires, specifically wheel balance. If mom in law never got above 50 mph the tires could be out of balance and no one would know.

If the car runs out smoothly at 65+ mph then no problem. If there is any vibration at highway speeds the first thing to check is the wheel balance on all 4 wheels.

If the mother-in-law never drove fast and did not maintain the cooling system, it’s quite possible that the engine will overheat on the firt fast trip. If I inherited such a car, I would have the cooling system serviced, oil and filter changed, transmission fuid changed and the brakes checked out. Inspecting the tires is a natural, since the ozone may have done a number on the rubber.

The ridge at the top of the cylinder is a concern if it is not removed before installing new piston rings. It is better to remove the ridge before removing the pistons. It doesn’t matter at all for new owners. If the engine could spin fast enough to matter, the Taurus would be going 190 MPH. That would be a miracle and the next miracle would be if the driver was believed.

I agree with Doc…again. Remember too that a motor runs at the same rpm at 25 mph as it does at 65 when it’s down shifted for acceleration. So it has some “experience”. I would be more concerned with the cooling system, transmission, drive belts, tires and braking system. Make sure those have been serviced as age related items. Organic oils do break down over time and brake discs rotors do rust as well when not used. I agree also that selling to a friend may not be the best friend retaining choice. But they could be upset if a cream puff were offered else where. A down to earth discussion about “low mileage” is no guarantee of reliability may be beneficial.