When I took my bike out of winter storage a few weeks back, one of the first things I did was change the oil.

I dropped into my local dealer and picked up a factory oil change kit, which included six litres of nicely packaged, semi-synthetic oil and a chrome filter. Cost: $81 with tax.

Considering a good-quality automotive engine oil sells for between $1.50 and $3 a litre and synthetic tops out at around $6 and a decent oil filter is in the $10 range at any parts store, this cost seemed a little excessive to me. It still does.

And so do motorcycle-oil manufacturers' claims of superior viscosity, better wear durability, enhanced coking resistance and all the rest.

Is motorcycle oil better than car oil? Do we need to spend such exorbitant premiums for it? Can we run car oil in our bikes?

Apparently, it may be a plot on the part of bike manufacturers to wring more money out of riders. At least according to John Woolum, a physics professor at Cal State University in Los Angeles and long-time rider, who recently conducted an extensive investigation into the ins and outs of motorcycle oil.

But first, a little background.

All four-stroke engine oil is rated by the American Petroleum Institute, usually with an S prefix: SF, SG, SJ and so on. In a nutshell, this rating indicates the viscosity and wear resistance level of the oil. Automotive engine technology has progressed so rapidly over the past decade or so, the petroleum industry has been forced to change the make-up of their lubricants to keep pace.

The slow-revving engines of the 1990s and earlier aren't as demanding as the high-output, multi-cam, computer-managed power plants being manufactured now, and regular old 30-weight just won't cut it any more.

Motorcycle manufacturers have always been quick to point out their engines run hotter and faster than car engines and must have a suitably durable lubricant to keep everything moving smoothly. That may have been true in the past, but it doesn't necessarily apply now.

The Honda S2000 sports car, for example, happily revs to 8000 rpm, which is more than most V-twin bikes.

During a one-year span, Woolum conducted a series of tests on one of his own bikes, a Honda V65 Sabre.

While logging distances of 1,200 km and 2,400 km, comprising 70 per cent city riding and 30 per cent freeway conditions, he sampled three car engine oils (Castrol GTX 10W40, Castrol Syntec 10W40, Mobil 1 Synthetic 5W50) and two bike oils (Spectro 4 10W40, Honda HP4 10W40).

Woolum's data found the two bike oils demonstrated inferior viscosity retention over both distances. In fact, of the five, they were at the bottom of the pack. Mobile 1 retained 83 per cent of its viscosity (the ability to flow freely) over the longer test and 86 per cent over the shorter run. Honda's own oil was down to 63.9 and 68 per cent, respectively.

Woolum says he's not picking on Honda. Most bike-makers market their own brand of oil, including Harley-Davidson, Honda, Victory, Suzuki and Yamaha -- and these oils are in turn manufactured by petroleum companies such as Shell or Chevron.

But bike makers charge a small fortune for their oil. Honda's in-house stuff is almost twice as expensive as Mobil 1, and other bike manufacturers are equally guilty.

Woolum found the average price of a quart of synthetic motorcycle oil in the United States was $6.53 (U.S.) compared to $3.53 for comparable car oil -- a price differential of 185 per cent across the board. In Canadian terms, this would come to about $10.50 a litre, versus $5.80.

Woolum's research showed synthetic oil, regardless of who markets it, is superior to conventional petroleum-based oil on just about every level.

The short version of all this is that you can probably run up-to-date automotive engine oil in your bike, once you know its specifications and requirements. But having said that, most bikes have a wet clutch and any oil with too many additives could cause slippage and other problems.

Which leads me to my own point of view.

Although I consider the prices charged by bike manufacturers for their own brands of oil outrageous and unfair, there's one important ingredient that comes with it: peace of mind.

You buy the oil/filter, put it in the bike and that's the end of it. With the car oil, you might or might not get the right stuff and could spend sleepless nights and anxious riding time worrying about it.

All things considered, it's probably money well spent, but still I wish they'd give us a break.