By Don Tupper, Tri Valley Automotive What is one of the most forgotten, yet is also one of the most well know services on a car? It is the first service due on a new car and also the most frequently done on any car. People know it, whole niche industries built around doing it quickly, the highest discounted and the lowest priced. Everywhere you look, there are coupons for it. I'm sure you have guessed it by now... The engine oil change. You knew that, didn't you? I'm also willing to bet you're probably overdue. Most manufacturers these days recommend changing your oil every 5,000 to 7,500 miles, some longer. Quickly...can you remember when you last had it changed? I know I can't tell you that, and I own a repair shop. You probably have to look on the window sticker or in your files if you're that organized (I'm not). I talk about all this because it is the single most important service on your car.  Do it frequently and your car will last a long time. The engine oil is the life-blood of your car and the oil filter is like your liver. (I know some people who would like to change their liver every three months, but I digress...) Keeping the oil clean helps the engine last longer, your car gets better gas mileage and runs cleaner, pollutes less.  All good stuff.  And I thought I would pass on a little bit more information than the standard "change it often" mantra everyone else seems to say. First let's talk about the oil. Most engine oil is just about the same these days. There are two major differences to note. 1. Standard fossil fuel type oil and 2. Synthetic type oil. There are blends of the two out there, but they aren't worth talking about. Most conventional oil is the same, only the additives differ slightly and you'll almost never see the difference. Synthetic oil leaves less deposits and overall lasts longer before breaking down, but it costs more. Personally, I use conventional oil in my daily driver and synthetic in my race car. The filter is an integral part of the oil system in your car. It should always be changed with the oil. What most people don't realize is the filter will clog long before the oil wears out. When that happens, a valve opens inside the filter and allows un-filtered oil to pass through the filter and straight to the soft engine bearings...not good. For this reason alone, the oil and filter should be changed on a regular basis.