Here's a little something to read that I stumbled upon while surfing info on Oil.
Ford, Honda and Daimler- Chrysler specify 5W-20 or 0W-20 motor oil for most gas engine powered cars and light trucks. Is 5W20/0W-20 oil really necessary?
Here are the technical facts behind 5W-20 and 0W-20 oil specs:
Question: My owners manual specifies 5W-20 or 0W-20 oil. Do I really need to use 5W-20 or 0W-20 oil and why did my 2000 model year vehicle require a 5W-30 oil, while the exact same engine in my 2001, 2002 and newer engines "requires" a 5W-20 or 0W-20 oil?
Answer: NO! You do not need to use a 5W-20 or 0W-20 oil. Do not let your dealer scare you by telling you that you have to use 5W-20 oil for your warranty. That is a tactic that some dealerships use to scare customers. Once you know the facts and the Federal Magnusson Moss Act law, you will be much better informed to protect your rights and use the type of fluids you want to use.
The main reason 5W-20 or 0W-20 oil was specified for your engine is to increase the CAFE (Corporate Average Fuel Economy) reported to the Federal Government. CAFE is the combined average fuel economy of all of a vehicle manufacturers product line. Minimum CAFE levels are specified by the Federal Government. In order for a vehicle manufacturer to continue selling profitable large trucks and SUV's, which typically have poor fuel mileage ratings, as compared to smaller cars, and still meet mandated CAFE requirements, they must also sell enough of the smaller cars which have much better fuel economy ratings to offset the poor fuel economy ratings of the larger vehicles. For model year 2001, the change to a 5W-20 oil will allow Honda and Ford's overall CAFE to increase by a very small amount, typically in the tenths of a mile per gallon range. 5W-20 oil is a lighter viscosity than a 5W-30 oil and therefore has less internal engine frictional losses, or less drag on the crankshaft, pistons and valvetrain, which in turn promotes increased fuel economy. This increased fuel economy is virtually undetectable to the average motorist without the use of specialized engine monitoring and testing equipment under strictly controlled test track driving when compared to a 5W-30, 10W-30 or a 0W-30 viscosity motor oil.
For better performance and protection we recommend using Signature Series 0W-30 100% Synthetic Motor Oil (SSO). This is the top performing AMSOIL Motor Oil for gasoline powered light trucks and passenger cars. It uses race-proven technology and provides unsurpassed fuel efficiency and better wear protection than other conventional and synthetic motor oils. It is a 35,000 mile/1-year change interval motor oil. Use it in conjunction with AMSOIL's Super Duty Oil Filter's that specify a change interval of 12,500 miles/6-months, whichever comes first.
Question: Could using a 5W-30, 10W-30, 0W-30 or even a 10W-40 or 20W-50, oil in my vehicle which specifies a 5W-20 oil void my new car warranty?
Answer: Absolutely not. Vehicle manufacturers only recommend using motor oils meeting certain viscosity grades and American Petroleum Institute service requirements. Whether a motor oil is a 5W-20, 5W-30, 10W-30, 0W-30, 10W-40 or 20W-50 (for racing and high performance applications in, for example, a Cobra R Mustang) or even a synthetic vs. a petroleum based oil will not affect warranty coverage. The manufacturer is required by Federal Law to cover all equipment failures it would normally cover as long as the oil meets API service requirements and specifications and was not the cause of failure. In addition, the Federally mandated Magnuson - Moss Act states that a manufacturer may not require a specific brand or type of aftermarket product unless it is provided free of charge. If your dealership continues to tell you that you must use 5W-20 motor oil and or/ a specific brand of 5W-20 motor oil, then ask them to put it in writing. Their position is inaccurate, and, in fact violates existing law.*
Additionally, if there is ever a question of whether or not a particular motor oil was the cause of an engine failure make sure to get a sample of the used oil in a clean bottle, typically 6 oz. minimum. The oil can then be sent to two independent testing labs for analysis. This is standard procedure for most commercial vehicles, trucking, construction/excavation and fleet companies and there are numerous certified test labs all over the country. Remember, a knowledgeable and informed consumer is your best defense against being taken advantage of by a car dealership service center.