One of the best things about modern cars is just how long they last. There was a time, not too long ago, when a car — especially an American car — was likely clapped out after 75,000 miles. A car or truck with over 100,000 miles or more on the clock? Forget about it, send it to the scrapper. Nowadays it seems that a car is just getting broken in at 100,000 miles, and it’s not unheard of for a new car to put down 250,000 or 300,000 miles without a major mechanical catastrophe. I’ve personally owned four cars that easily hit the quarter-million mile mark — a Cadillac, two Mazdas, and a Saturn — and while I know that the plural of anecdote isn’t data, that’s still a pretty good ratio.
Now, the thing about cars when they get old enough is that their diet changes, so to speak. Much like when you get past a certain age you need more vegetables and vitamins than pizzas and beer, older cars need different kinds of fluids than they needed when they were fresh off the lot. So, what do you feed a car Of A Certain Age? Probably the most important thing you can give your elderly car, aside from regular maintenance, is high-mileage engine oil.
What exactly is high-mileage oil and when should you use it? Do you even need to use it? I’m glad you asked.
Keeping your car regular
High-mileage oil contains a mixture of seal conditioners, additives, and detergents — the actual mixture depends on the manufacturer and product line. The seal conditioners help reduce small leaks inside and outside of the engine by causing old gaskets and o-rings to swell up and seal better. The additives grant protection to things like cylinder walls and cam lobes that do a lot of heavy lifting at high speeds and temperatures. Finally, the detergents work to clear sludge and gunk out of all the engine’s nooks and crannies (or, well, they claim to at any rate).
When should you use it? Well, that kinda depends on how and where you drive. Highway driving is a lot easier on an engine’s internals than the punishing grind of stop-and-go city driving. An engine with, say, 150,000 highway miles on it may still be in top condition while the same engine only driven in the city might be tired out by 80,000 miles. Depending on the manufacturer, high-mileage oils are recommended when a vehicle has between 75,000 and 100,000 miles on the clock. Your best bet is to ask a trusted mechanic their advice on the subject, especially if they’re familiar with your car.
What high-mileage oil is not is a panacea. It will not cure mechanical damage like heavily worn rings, burnt valves, blowby, rod knock, power loss, etc. Nor will it plug up heavy leaks, stop a car from smoking, or fix non-oil-related issues. It is cheap insurance in the form of preventative maintenance, however. Should you use high-mileage oil? Sure, especially if you have a well-maintained, high-mileage engine. Spending a few extra bucks per oil change on high-mileage oil is way cheaper (and, honestly, smarter) than shelling out for a new engine, or god forbid, a whole new car.
