We've been discussing Oil A LOT and I figured it was time to make a thread dedicated to oil...
Oil weight, or viscosity, refers to how thick or thin the oil is. The temperature requirements set for oil by the Society of Automotive Engineers (SAE) is 0 degrees F (low) and 210 degrees F (high).
Oils meeting the SAE's low temperature requirements have a "W" after the viscosity rating (example: 10W), and oils that meet the high ratings have no letter (example SAE 30). An oil is rated for viscosity by heating it to a specified temperature, and then allowing it to flow out of a specifically sized hole. Its viscosity rating is determined by the length of time it takes to flow out of the hole. If it flows quickly, it gets a low rating. If it flows slowly, it gets a high rating.
Engines need oil that is thin enough for cold starts, and thick enough when the engine is hot. Since oil gets thinner when heated, and thicker when cooled, most of us use what are called multi-grade, or multi-viscosity oils. These oils meet SAE specifications for the low temperature requirements of a light oil and the high temperature requirements of a heavy oil.
You will hear them referred to as multi-viscosity, all-season and all-weather oils. An example is a 10W-30 which is commonly found in stores. When choosing oil, always follow the manufacturer's recommendation.
Q. What is oil sludge?
A. Oil sludge is the breakdown product of over-stressed oil in your engine.
Oil that is stressed by contaminants and oxidation-or has to work thousands of miles longer than it was designed to-will break down into a gel that sticks to your engine parts. As the sludge sticks, there is less good oil to circulate and do its protective job. This coating of gel also stores heat instead of releasing it which stresses the radiator and cooling system.
Although at first the motor oil level may appear OK, a sludgy engine is being damaged with EVERY stroke. Your engine may lose oil pressure, get terrible gas mileage, and other components might mysteriously fail such as timing belts, idle speed controls, and gaskets.
Sludge begins to appear in the oil pan and valve covers. Oil filler cap inspection as an indicator of sludge build-up is not conclusive, as normal engines can have a small amount of sludge and condensation present at this 'high point' of the crankcase.
Q. How often should I change my oil?
A. Always refer to your FSM for information pertaining to oil change intervals and viscosity's as every motor may be different.
Q. Is it bad to change from a Conventional Oil to a Synthetic Oil?
A. NO. Defective seals cause seal leaks, not synthetic lubricants. Unfortunately, this myth is still being perpetuated today by people who know little to nothing about synthetic lubricants. Why is that when a seal leak develops when conventional oil is used and it's the seal's fault, but when a leak develops using synthetic lubricants the synthetic lubricant is the suspect? Synthetic lubricants are required to possess the same seal compatibility characteristics as today's conventional oils. Often car owners do not realize that they have a seal problem when using ConventionalWi oil. Conventional oil will often volatize or coke around a seal defect, leaving little to no evidence of a seal leak. Synthetic lubricants however possess a very high thermal stability and resist evaporation. These exceptional performance characteristics, coupled with synthetic lubricant's inherit "creeping" ability, will unmask a seal leak not readily visible before. Although old synthetics used Mineral oil when sythetics first arrived. Which in turn caused Seal Swell and you would leaks quicker than a Conventional Oil. But since they took the mineral oil out of the synthetic, the seal leak is a non-issue today.
Q. Should I Switch to Synthetic Oil?
A. You should only switch to synthetic lubricants if you want better equipment performance and longer equipment life than a conventional oil. The advantages you'll get with synthetic lubricants include:
* Dependable and easier cold weather starting.
* Increased thermal protection reducing the likelihood of engine overheating.
* Increased fuel economy.
* Better throttle response and increased power.
* Improved exhaust emissions.
* Longer oil drain intervals without compromising engine life.
* A cleaner engine.
* Significant reduction in engine wear.
Q. Will switching to a Synthetic Oil give me better gas mileage?
A. Yes, you should see a slight gain in MPG. The reason is that the synthetic oils lubricate the motor better than conventional oil
Q. I have dark oil, is that bad?
A. Dark oil does not indicate the need for an oil change. The way modern detergent motor oil works is that minute particles of soot are suspended in the oil. These minute particles pose no danger to your engine, but they cause the oil to darken. A non-detergent oil would stay clearer than a detergent oil because all the soot would be left on the internal engine parts and would create sludge. If you never changed your oil, eventually the oil would no longer be able to suspend any more particles in the oil and sludge would form. Fortunately, by following the manufacturer's recommended oil change interval, you are changing your oil long before the oil has become saturated. Remember, a good oil should get dirty as it does it's work cleaning out the engine. The dispersant should stop all the gunk from depositing in the oil pan.
The only real way to determine whether oil is truly in need of changing is to have an oil analysis performed. Since most people don't want to bother with this, it's acceptable to err heavily on the safe side and simply follow the manufacturer's recommended change interval for severe service. There are still a few cars that specify 3K intervals for severe service, but not many. If you look at countries other than the U.S., the oil recommended change interval is much higher than even the normal interval specified by vehicle manufacturers in the U.S.
Q. Should I Pay someone to change my oil or do it myself?
A. The dealers also offer a time guarantee, generally that they'll get you in and out in less than 30 minutes or the next oil change is on them. Another advantage of having it done at a repair shop or dealer is that you have solid legal proof of the date and mileage when the oil change took place. My personal preference is to have the oil changed at a dealer during the warranty period.
After the warranty is up though, I recommend getting a few tools and doing it yourself. Oil is inexpensive and easy to change. And if you do it right, you will have a peace of mind. I've seen some pretty sketchy shops with in-experienced techs that put the wrong oil in vehicles before (Jiffy-Lube Houston, TX). If you know what oil is going in your car and trust your tech though and don't feel like getting dirty, feel free to use your trusted mechanic. If not, I would fray away from bringing it to someone who you don't know their experience or expertise.
Q.5w30 vs 10w30.. which is better?
A. Virtually all new passenger vehicles sold in the U.S. use either 5W30 or 10W30 oil. The difference between the two is that the 5W30 flows better when cold, so if you live in a cold climate or operate your vehicle in a cold climate during the winter months, you should use 5W30 if it is the preferred oil for your vehicle. If you live in a sub-tropical climate and don't operate your vehicle in cold climates, then 10W30 is acceptable as long as the manufacturer specifies that it is permissible to use it.
When I say cold too, I am talking below 0 degrees Fahrenheit. Most locations in the USA generally do not get this cold.
Q. How much is too much oil?
A. Your dipstick has an indicator on it L for low range H for High Range. Your oil level with the motor COLD should be in between the L and H Indicators on the dipstick. If it is too low, you can risk internal damage due to low oil pressure and heat exchange. Adding too much oil can overfill the crankcase. As the crankshaft spins around, it will spin the oil around and create air pockets in the oil if the level is too high. (kind of like a foam in a way) This, in turn, can cause a drop in oil pressure and loss of lubrication to critical engine parts. Also, too much oil may cause leaks as the extra oil is forced past seals and gaskets.
If anyone would like to add any additional information on here, please feel free to do so
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If you have an hour or so to read this 120 page PDF, its very insiteful and has a lot of information about motor oil