A good piece of automotive advice for older engines is to think about using engine oil stop leak. Some states, like California where I grew up, have emission laws that are very strict. Oil leaking into the combustion system and coming out of the tail pipe as dark smoke will definitely cause your vehicle to fail its smog test. But before you try stop leak for your engine, lets first find out what it is. Stop leak for engines is not the same kind of stop leak for things like leaky tires or radiators. Stop leak for engine oil isn't a goopy substance like many other leak stopping substances. It supports the rubber seals in your engine that wear out naturally with time, which you'll read about in the next section.

Inside your engine, there are moving metal parts, such as pistons. When these metal parts move against one another, they cause friction, grinding, and heat. That's where motor oil comes in. Motor oil is the lubricant for the metal parts to flow against each other without causing too much frictional heat or damage to the motor's interior. There are seals within the motor and gasket that keep the oil confined to where it's supposed to be. The problem is, these seals wear out over time, and oil begins to seep into places it's not supposed to be. When this happens, it usually doesn't cause any major problems, but generally causes a slow oil leak, and very smokey combustion. If you have ever been behind an older car that has dark smoke coming out of its exhaust, you've most likely witnessed some leaky oil seals in action, which are letting some of the oil into the combustion system. Engine oil stop leak works by treating the seals that keep the oil in place. They soften the rubber and cause it to expand, closing up tiny cracks and spaces where the oil can sneak through.

It's generally easy to figure out if you need stop leak. If you have a puddle of oil beneath your car but don't have any smoke or odors of burnt oil, then you probably don't need stop leak. What you probably have is either a ding in your oil pan, a loose oil filter, or a bad drain plug. Even so, engine oil stop leak won't hurt your engine at all, and may in fact keep your seals alive longer. Just in case however, it isn't a bad idea to use. As cars age, mechanics generally recommend a stickier form of motor oil anyway, something more viscous. New cars generally get 5w-30, or 10w-30 oil with their oil changes, either fully synthetic or partially synthetic. In colder climates, sometimes cars operate on 0w-30 oil that still flows well in cold conditions. Once cars start to age, the viscosity of the oil generally goes up. In older cars, the oil viscosity starts to go up. Sometimes single weight oil is used, such as single weight 20, 30, 40, even 50, but these are no longer used in today's engines.

Why is this important? If your car's engine is getting high in miles, you may want to first switch to a higher viscosity oil. If you've traditionally used 5w-30 oil, try 10w-30, and so on. The next time you go for an oil change, tell your mechanic that you're worried about a potential oil leak and were wanting to switch to a slightly heavier oil. Even if you aren't yet experiencing an oil leak, it's good to be proactive. If you have well over 100,000 miles on your car, think about going up to the next higher viscosity of oil.