One of our readers asked us this question the other day. Why can semi trucks go for a million miles while most cars struggle after 200,000?
You are talking about “long haulers.” These guys and gals drive 8 (previously 12) hours a day with 90% of it being on the highway in their highest gear. This doesn’t actually put a lot of strain or wear on the vehicle. “City haulers” on the other hand drive stop-and-go and wear their trucks out significantly quicker.
Another answer is they are true diesels. All diesel engines have major advantages over gasoline engines. Diesel car engines have lasted 750k+ miles many, many times (proper ones, European cars almost exclusively). In the USA we got fooled by crap diesel cars we designed from gas engines, but that’s another topic.
Proper diesels use compression firing instead of super hot spark plugs. Diesel is an oily fuel and lubricates whereas gasoline is “dry” and solvent-like. Diesels run cooler. Diesels have loads of torque at low RPMs. Add all this up and you have cool, oily, metal that moves at lower RPMs. Good things for metal engines.
Most commercial semi-trucks get regular preventative maintenance to keep them on the road longer. A typical car owner wont seek maintenance until there is a noticeable problem. However, most consumer base Diesel truck buyers/owners will take care of them.
If the average car driver were to maintain their car motor every 15,000 miles, their motor will outlive them.
So what exactly can you do to make a car run this long?
Not a whole lot of things. One of the best things you can do for your car is change the damn oil. Lots of people do not change the oil regularly enough. Change the oil (with the correct viscosity and grade of oil) and the oil filter. Old oil can clog oil journals so parts of the engine don’t get pumped to them causing premature wear.
Change the brake fluid once every two years. It’s not about how much you use the brakes, just the fact that in that time it will lose its properties due to moisture absorption.
Change the engine coolant once every three years, or get the long life stuff so you have to change it less often.
Change the consumable items when they need replacing or just a little before. That’s things like brake pads, brake disks, tyres, air filters, spark plugs and so on.
Get the major service work done. Things like cam belt changes and valve clearances. Expensive to pay for and not impossible to do yourself if you’re mechanically minded and willing to learn. Even if you pay someone else, it’ll make the car last because the major mechanical components will remain in good order.
Look after the car. Don’t neglect it. Don’t ignore warning lights. Check the car daily before you drive. Clean the car every now and again, clear out the gutters and things. Keep the road salt levels down.
Drive the car properly. If you’re kind to the car the car will be kind to you or well your wallet. If you rag it everywhere you’ll knacker the thing out pretty quickly. If you drive it sensibly then you’ll find that everything lasts longer, the consumables, the more major things too. Don’t dry steer. That is steering whilst stationary. Easy to do with a power steering car and a lot more common these days. There really is no need for it and you just put needless stress on the steering linkages and power steering pump.
If you really want a car that’s going to work well and last longer with good driving I suggest that if you can’t now, learn to drive a manual. The gearboxes are a lot hardier and cheaper. The only thing they should need in time is a clutch replacement but if you drive it properly they should last 100 to 150k miles.