This is it... He told me unless you ride your bike every day, you should use dino oil.  I asked why.  He said that dino (organic) oil stays in the bearings and journals and much better than synthetic when the bike is turned off. He told me synthetic will drip down and run off of the bearing surfaces after a couple of days leaving the bearing high and dry.  Then a few days later when you go to start the bike, the bearing is dry and damage is the result.  I told him I had heard just the opposite.  He said if I didn't believe him, I could run a test by using two large nails.  Dip one into dino oil and dip the other into full synthetic.  Put them outside and hang them from strings on a branch for a few days.  He said the one that was dipped in dino oil will still have a coating of oil on it while the one dipped in synthetic will not only have no oil on it, but it will most likely have a minor coating of rust.  He also said that if the clutch plates are at all worn, the ultra-slippery synthetic may cause clutch slippage.  He said that this drain-down of synthetic oil is particularly critical in engines with plain bearings (like Vulcans).  Harley uses roller bearings and as soon as you start the engine, oil is splashed up on the bearings to keep them from running dry.  So, as a result of this conversation, I am sticking to Spectro motorcycle specific organic oil and I will change it often.

I am sure that many guys will strongly disagree with me, but the tech seemed knowledgeable and honest.  If you decide you still want to use synthetic, stick with the blend and don't leave the bike idle for long periods of time.

How can you tell the difference between sludge and varnish? Sludge is a wipeable deposit, meaning if it wipes off,  it's sludge. It can range from a thin film to several inches deep.  If it doesn't wipe off, it's varnish.  Varnish is a thin, translucent deposit ranging from a pale amber to black. I've seen and rated many engines that had both sludge and varnish accumulation that were run on synthetic lubricants.

In general, you usually get sludge in cooler running engines, varnish in hotter running engines.  We do our best to destroy oil (both ours and our competition) everyday in our engine test lab, and we're pretty good at it!    :-)

The act of constantly switching from one oil brand to another has nothing to do with the accumulation of sludge, gum, or varnish. This is what causes all three of them: Conventional (non-synthetic) oils are refined products from naturally produced crude oils. The refining process is not a perfect process in that it is not possible to remove all of the asphaltines, paraffins, and ash from them. The highest grade, most pure, conventional oil on the market is Pennzoil. But even Pennzoil is only 60% lubricant. That means that a whopping 40% of the product is something other than lubricant that could not be removed during the refining process. This is the material that chemically reacts with engine gasses and produces sludge and varnish. This is why you will never have sludge or varnish in an engine that uses synthetic oil such as Mobil-1. Synthetic oils are manmade and are 100% lubricant plus a few non-reactive additives for enhanced stability. There is simply nothing
in synthetic oils to react with the engine gasses to produce sludge or varnish.

Quaker State oils are notorious for producing varnish! They have some of the lowest quality refined oils on the market. The only way you could do worse is to use one of those recycled motor oils that you can get dirt cheap through WalMart.

If you want to truly protect your bike, you have two choices: 1)Use a good Synthetic oil and change it out every 3000 miles. 2) Use a high grade conventional oil or synthetic blend and change it out every 2000 miles which is before the unrefined contaminants can break down and deposit sludge or varnish in your engine.

One more thing: The motorcycle oils by Kawasaki, Honda, and others are all very good oils and you can't do wrong by using them. Remember though, that they ARE conventional oils and must be changed often to prevent sludge and varnish. Contrary to what your dealer may tell you, it is not necessary to use a motorcycle oil in your Vulcan. The V-Twin is a low RPM engine and does not require the special zinc additives in motorcycle oils that are needed in the high-revving sport bikes.