Shell rotella in f115 outboard 4 stroke

First off let my appologize as I am sure the age old oil question has been beat to death.

I am new to outboard maintenance but I am an advid motorcycle enthusiest (? spelling) and do all my own maintenance on my bike.

The warrenty on my sister's pontoon ran out and she doesn't want to have he dealer service the engine any more and wants me to take over the maintenance.
$150 for an oil change?
Maybe that's the going rate, but that's quite high to me.

It's time to change the oil and I was wondering if anyone is using either Shell Rotella 15w-40 dino oil or the new T6 full synth 5w-40.

I am active on a couple of motorcycle forums where lots of folks are using both and have for quite a while.
I have run the T6 full synth 5w-40 for the past 8,000 mile myself.

I know I'll catch a lot of grief for asking and I know that the Yamalube costs maybe $20 more for an oil change, but the Rotella is more readily available and I know it's a good, stout oil.

I don't know anything about the Yamalube except it costs twice as much.

Also, are there any oil filters that are compatible with the F115 besides the Yamaha filter?
I know that there are a lot of motorcyclists that use the Purolator PL14610 & PL14612.

So, please pardon my noob question.

Any and all input is appreciated.

Thanks.

If your sister likes her F115, then spend the money and purchase the Yamaha oil and filters. The cheap person pays 3 times.

Go to Walmart and buy a jug of Mobile 1 synthetic. You are correct... The oil debate has been going on and on about this and that. Many have been running Mobile 1 synthetic for years including me. Foaming? C'mon.. Mobile 1 works in Formula 1 cars that rev to what? 18,000 RPM? Some kinda additional rust inhibitor claim and such with Yamalube? Give me a break... It is a closed and sealed system and if there is saltwater getting into my oil I have major problems. Just change your oil at the end of every season before you put her to bed for the winter and forget about it. By the way... 2002 F115 4 stroke here running just fine on Mobile 1 synthetic for years. I do purchase the Yamaha oil filters online.