Mr. Green Car: Oil philosophy 101
By Allen Penticoff
We’d all like our cars and trucks to run at their best and last a long time. Other than consistent washing of the body, the next best thing you can do for the life of your vehicle is regular oil changes.
Recently, a discussion about oil and oil changes broke out on my front deck while watching the Rockford AirFest. Everyone had a different take on what oil to use and how often to change it. One member of the discussion uses synthetic oil, while another, a professional mechanic, does not believe in the stuff much. I, myself, have been on the fence about its value for a long time.
First, there are two schools of thought on oil changes. One is frequent changes of inexpensive mineral oil, the other is that you can go much longer between oil changes with more expensive synthetic oils—picking up synthetic’s positive features of superior cold starting and high heat tolerance, and ameliorating the additional cost by not changing the oil so often.
Some service garages and most quick oil change “specialists” still recommend 3,000-mile oil changes (more changes equals more money) despite most modern vehicles having their owner’s manuals recommend changes at 5,000 to 10,000 miles and greater.
Some new models have “Oil Life Monitors.” OLMs use the engine’s computer analysis of engine experience to make a recommendation via a “change oil soon” light. I’ve suggested that you follow those recommendations, with the caveat that you’ll need to monitor your oil level more often so as to not exhaust the oil in the engine.
My mechanic friend has seen several engines destroyed because the owner never checked oil awaiting the change light to come on. Checking the dipstick once a month would do on most vehicles. (Airplane pilots usually check the oil on every flight.) Personally, I use a 5,000-mile interval on most of my vehicles as it is a compromise between the old-school 3,000-mile interval and the 7,500-mile interval the manual calls for—it is also much easier to know when the oil needs to be changed when the odometer hits a multiple of 5,000.
If you drive very little, ironically, you may need more frequent oil changes, even based on calendar time, as an engine that never warms properly will not burn off contaminants in the engine.
My Mr. Goodwrench friend, Dan, changes the oil at 2,000-mile intervals on his personal vehicles, believing there is nothing better for an engine than clean oil. He also has access to a lift and all the stuff to do a change quickly at minimal cost. I won’t disagree that this oil change frequency may make your engine last longer, and if you’re shooting to drive your car for a million miles (and a couple have made it to almost 3 million miles), this may be the way to get there. I think my compromise between convenience and economy is reasonable.
It is my experience that there is not one bit of practical difference between brands of oil. As long as the oil meets or exceeds the American Petroleum Institute (API) service rating (SM is better than SL or preceding lower letters of the alphabet) recommended by the manufacturer (and nearly all oils you’ll find on the shelf do), buy what is least expensive—most of the rest of the price difference is found in advertising costs. It is also acceptable to mix brands as long as the viscosity numbers are the same (best) or fairly close to the same (OK). A new label, the API “star,” indicates the oil as conforming with SM/ILSAC GF-4 fuel economy test standards.
The most important thing is to not run out of oil, so if an “oil” warning light comes on, which is an indication you’re about to run out of oil—stop immediately and check for massive leaks, and the dipstick. If the dipstick is dry, this calls for serious consideration of proceeding further. Discuss with a mechanic ASAP. If no major leaks are found, the oil probably was burned off low, and simply filling the oil up will get you going again. If desperate, any oil is better than nothing.
As long as you regularly change ordinary “detergent” mineral-based oil, you won’t have “oil sludge” problems, so that “advantage” of synthetic does not seem to play well. Don’t know which way to go? You can try a semi-synthetic oil that is a blend of the two—up to about 30 percent synthetic for a price between the two.
Marketers of synthetic oil claim instant increases of power and fuel economy along with considerably less wear. Snake oil? Not really, but many of the claims are exaggerated, largely because our engines rarely are used at full power. Also, in many engines already with high mileage, real problems can occur with switching from mineral oil to synthetic. This is a decision to discuss with a very knowledgeable service technician. If a vehicle manufacturer recommends/requires synthetic oil, there is a good reason, and I’d not try to go cheap with using mineral oil—ever. In the end, follow what the manufacturer recommends—it is a safe bet.
We’ll continue this discussion in the next installment of Mr. Green Car (Sept. 9 issue) as we look at synthetic oil more closely in “Oil Philosophy 102.”
from the Aug. 26-Sept 1, 2009 issue
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