5W-20 oil


Should I use 5W-20 syn. oil in my 2001 Nissian Altima. It calls for 5W-30. Looking for better gas milage.


That’s more of a personal call.

You have to look at if you’re going to gain enough in fuel mileage to cover the extra expense for synthetic oil. And I doubt it.

Synthetic oils are more application specific because of their stability characteristics. So if the engine is operated in severe conditions such as when towing heavy loads, severe temperature conditions, racing conditions, or if the engine is equipped with a turbo-charger, there is a benefit in using a synthetic oil. Other than that, there’s really no benefit in using a synthetic oil.

And if you’re wondering if you can go longer between oil changes using a synthetic oil? Just look in your owners manual. Nowhere does it state that there’s an exception in oil change intervals when synthetic oil is used.



You won’t get enough to make a profit. Front end alignment and tires with low rolling resistance (Consumer Reports again) could help. More tire pressure too. Keeping the speed and acceleration down will help as well as taking your foot off the gas when you get close enough to the stop sign to coast.


Agree with other posters that any gain in gas mileage is minuscule. The reason for using synthetic oil is to get longer engine life, especially under extreme conditions. Your driving style and condition of your car (tire pressure, wheel alignment, and other items) determine your fuel mileage. Gentle driving, not jumping on the brakes the last minute, keeping speed sensible all give you better mileage.


I read somewhere that Ford estimated their fleet average increased by .5 miles per gallon (MPG) by switching to 5w20 from 5w30.

If your mileage improves by .5 MPG from say 25 to 25.5, and you change your oil every 5000 miles, then you would save almost 4 gallons of gas between oil changes. Around here you can buy Motorcraft 5w20 synthetic blend for about $2.00/quart (everyday price at Walmart).

A 5000 mile oil change interval on a synthetic blend should be no sweat under most conditions.


That .5MPG on a simulated EPA laboratory test will give Ford more opportunity to sell higher profit SUVs and large cars without incurring penalties. As posted elsewhere last week, the US is the only country in the world with specific corporate fuel mileage (CAFE) standards with penalties. The 5W20 oil switch is not in the interest of long engine life under adverse conditions. My Toyota has the same tight engine clearances as other modern cars, but Toyota calls for 5W30 oil, since they sell enough small cars to have no problem meeting the CAFE standards.


Since the OP does not mention adverse operating conditions, they may still find the fuel savings attractive.

FYI, Toyota now recommends either 5w20 or 0w20 for all their 2006 and 2007 cars. This was specified in technical service bulletin EG018-06 dated Mar 26, 2007. Here is a link:


I suggest using what’s recommended. While 5W20 has a teeny bit better lubricating characteristics than 5W30 (the polymer viscosity enhancers don’t lube as well as the base oil), 5W30 also has better ability to maintain viscosity at temperature.

I have to believe that the manufacturer knows best. You might get a teeny bit better mileage at the cost of reduced engine life.