Oil Change time, I have questions?

[ride92]

I'm thinking of changing the oil soon in my bike. It may have been done last fall when I had a guy tune the cars but can't really remember if he said he did so or not. I've been reading thru the oil thread and filter threads and am still a bit confussed on what to use. One thread mentions that a puralotor L14610 filter will fit our bikes. It just so happens to be the same filter that goes on my mazda!!! Actually it's suppose to be the L14612 but the L14610 is a bit loger and provides more surface area to filter the oil, and I have a few sitting in the garage. Has anyone used that filter on the seca before? I know not to get the pureone for the bike.

Also, I'm aprehensive about what oil to get. Seems like quite a few people run the Rotellla oil either the T or T6, What weight should I be using for mostly summer riding and bit into the fall when temps dip a bit. I ussually don't ride if the temps are under 40 degrees. Other then those to oils is any oil marker 4T meeting the specs for oil for the bike? I run synthetics in my '03 mazda and generally buy into the advantages of synthentic but for a 21 year old bike am I going to run into issues switching now? I've always heard to stay away from sythetic for older cars as the oil is too fine and will start to seep thru the seals and gaskets in older engines in cars since there tolerances aren't always as tight. Does the same hold true for the seca engine? I'd hate to change to synthetic only to have to go thru the engine and start replacing a bunch of seals and gaskets. Please advise me!!!