Oil Change Time? Will That be “Regular” or Synthetic?

A friend of ours made a “Bonsai” run from Washington to Arizona for a quick visit. We thought maybe he’d been for a revamp at the peacock factory when he strutted around, talking about how much fuel he’d saved on the trip by making the switch to synthetic oil. His glowing reports were so impressive, what with an oil change due on the “round town car,” the family mechanic decided to give it a shot.

This being the first time we’d ever purchased anything other than good old “regular” mineral oil, the ring up at the cash register was breathtaking. Even with the “buy the oil and get the filter nearly free” special, it seemed like we were paying nearly twice the dollars for this “syn oil” change. “But hey! Think of the money we’ll save with the increased fuel economy.”

Knuckle heads.

If anybody has preached about the business of “checking out the story before you jump,” it would be this family mechanic. It didn’t take many hundreds of miles on the new oil before the light turned on, and a little bit of research to be done. All that crowing for a 2 to 4 percent increase in fuel economy? Let me run the numbers.

Before switching to synthetic oil, our little buggy averaged around 28 miles per gallon. By “upgrading” to synthetic oil, even to the high side of estimates for increased fuel economy given by many syn advocates is a 4% increase. That would mean a possible increase to 29.12 miles per gallon. Assuming an oil change at 5,000 miles, we’d burn 172 gallons of fuel. With regular oil, we’d anticipate using 179 gallons. So with syn oil we save 7 gallons of fuel, or at current fuel charges, about $16.00.

OK, with regular oil at about $3.99 quart, and the corresponding grade in synthetic at about $8.99 a quart, it’s costing me about $25 more per oil change–in plain old dollars and sense, I’m sure not saving. Here’s the argument put forth by synthetic oil promoters: “AMSOIL synthetic motor oils (excluding the XL motor oils) may be used for intervals of 25,000 miles or one year whichever comes first.” Ah, you actually save money, because you change the oil less!

“Not so fast!” Says our car manufacturer. To keep the warranty valid, we must continue to observe the required maintenance schedule–5,000 mile oil changes–regardless of whether the stuff is mineral oil or synthetic. And the same could very likely be true for your rig. Yes, we know that the synthetic advocates will tell you your engine will “wear” better if you use the synthetic, but hey, if something blows up before your warranty expires, try and tell the engine manufacturer that.

So what’s the bottom line? If your rig is still under warranty, you’re definitely stuck changing your oil at the required interval. To our way of thinking, that makes the whole thing a no-brainer: Use the old-style motor oil; sure, use the “lightest” viscosity you can for the temperatures you’ll be encountering–that in itself will save you money. If your warranty is a thing of the past, then consider going to the “long change” idea advanced by the syn-oil advocates. But beware, you’ll still need to change your oil filter at required intervals, as that bad boy will still be filtering out crud, and once it’s full, it’s not working to protect you.

Meanwhile, we’re still licking our wounds over that costly oil change. Maybe we should drive to Washington and back and see just how good it gets.

photo: 91RS on flicker.com