The rule of thumb as I know it for oil is:  if it has a filter, use detergent oil; if it doesn't have a filter, use non-detergent oil.  Your vee drive has no filter, so no detergent.

For the engine, use heavy duty 15W40 oil that has an S (for spark engine) rating.  A lot of us use Delo diesel oil that is rated both C (compression engine) and S.

09 Wakesetter with a zf ski1000 throttle

When in neutral, the transmission is actually slightly in reverse. Reverse still works as expected. Moving to forward, there is a small dead spot then a jolt into gear. Is there a way to adjust these throttles? 

6 hours ago, BluBu09 said:

she is praying like a kitten once again

I don't know how kittens pray, but I'm sure it is a good sound.

2 hours ago, Rabby said:

I opened the fuel cap today and there was a big suction of air into the tank like it had pressurised as fuel was being used. 

I would address this first.  The tank has a vent system that allows air to come into the tank to displace the volume of fuel leaving the tank.  If the vent isn't working correctly, the pump will not provide the proper fuel pressure as it must pull harder and harder to get fuel from the tank.

I don't really know how the vent system works on your boat, but it should have a small vent at the transom.  Check to make sure that it isn't blocked by something.  Here in the southeast US, mud dauber wasps are notorious for plugging tank vent ports.  Perhaps you can gently blow into the filler port to see if the vent is open (blow like trying to inflate the tank).

Fluctuating temps checklist - 1. Debris in inlet side of trans cooler. 2.  As noted air leak on inlet side,  3.  Malfunctioning thermostat,  4.  Circulation pump impeller failure.  5. Clogged or loose water strainer,  6. Shredded raw water impeller or leaking O ring (air leak).