The dry sump design of the 500 engine allows the engine to have slightly more hp without the burden of sloshing around the extra weight of oil in the engine cases plus having it return to the tank allows the oil to oil to cool down a bit before it's returned through the engine! The easiest way to drain the oil plus the 8 ounces of oil in the engine sump is to drain the oil tank,then crank engine for 15-20 seconds only,then kill it!! This pumps out the additional sump oil out of the tank, then remove the old oil filter for the remainder! If you just drain the tank, oil is left in the engine.The engine does have a sump drain on the side,but hard to get to! I've used this way on oil changes for years on the 500. Tell your friend to use only 0w40 OR Polaris PS4Plus 2w50 as any thing thicker can shorten the cam life as it already is in the year model group with the soft heat treated cams! 1996-2000 were the problem years!I've had customers that have used Klotz octane booster and oil products,but don't know if they make a 0w40 oil? The 500 takes TWO quarts oil only! This is after all oil is drained! If sump isn't drained,then dip stick will show overfull! Run the engine after filling for at least 3-5 minutes before you check the dipstick level! PS the sportsman 500 didn't come out until 1996,guess you transposed the "89" Sportsman 500? 98 model maybe? I do this myself quite a bit OPT