If you want to purchase a used semi truck, then it is in your best interest to look at the truck you intend on purchasing very carefully. Semi trucks are quite expensive, and even used varieties can cost as much as $100,000. It is often suggested that you look at the maintenance logs before deciding on the truck you want. There are a few things you should look for in these logs, like the following.
There are many types of high-quality oils that are now produced that help to meet the demands of commercial vehicles. Commercial vehicles used to need oil changes as often as every 500 miles, but trucks may not need their oil changed now until you drive about 50,000 miles. While this is true, high demands typically dictate an oil change at around 25,000 miles. Make sure that logs indicate that this has happened regularly over the lifetime of the semi.
In some cases, you may see oil changes that happen between the 10,000 and 15,000 mile mark. This may mean a few different things. For instance, the semi may have been supplied with low-viscosity oil to help improve fuel economy. This type of oil can leak around the engine seals and burn off more quickly than thicker oil, which may lead to the need for more timely oil changes.
The purchase of cheap and inefficient filters as well as extreme driving conditions can cause debris and contaminants to build up within the lubricant. This may be a sign that the semi engine has been subjected to a great deal of wear and tear. It also may be a sign of impending engine failure. For example, if glycol contaminates the oil, this causes the lubricant to become more susceptible to soot accumulation and clumping. Also, the oil will be able to degrade and oxidate much more quickly. If these things happen, then the oil will need to be changed more often. The contamination is a sign that head gaskets have cracked or engine seals have deteriorated to the point that coolant has started to mix with engine oil.
If you notice an unusual oil change record, then speak with the truck seller about the reasons why the changes have been scheduled this way. This will help you to determine if the semi is worth your investment, if further investigation is needed, or if you should look elsewhere for a truck.
Engine rebuilds and replacements are often a necessary evil when it comes to owning a semi, and a rebuild can cost $20,000 or more. Depending on engine demands and general upkeep schedules, some semi engines can run well even after they've been driven 1,000,000 miles. However, many engines need to be subjected to careful inspection around the 750,000 and 800,000 mile mark, because this is about when the average semi engine needs a rebuild.
Maintenance records will clearly show the mileage of the semi and whether or not a rebuild has been completed. In some cases, a partial overhaul may have been performed, where piston rings are replaced, cylinders are refinished, timing chains are replaced, and guides are replaced. While these things can certainly extend the life of an engine, they will not completely prevent engine failure. Engine failure may occur soon and lead to an expensive repair.
If the engine has reached the 800,000 mile mark and a rebuild has not been completed, then take a test drive and look for signs of impending failure. Look for black or blue smoke coming out of the exhaust for an extended period of time when you start the truck and also listen for knocks or bangs coming from the idling truck. Try to notice if the semi lacks power, is hard to start, or does not run well at lower RPMs.
Contact a company that specializes in semi truck sales to learn more.