Need advice. Just bought Kawasaki STX15F 4-stroke

[Ninjaracer636]

I just have about 2 hours on it but have a few questions. As I understand it needs 10w-40. I'm not sure if there's a particular brand that's required. Also regarding maintence, everything is in hours so I just wanted an idea on how that would compare to miles. Also wanted to see when to switch to synthetic.

Some details.

1500cc 4-cyl 4-stroke
inducted water cooling (should run cooler than a car/motorcycle)
7500 rpm redline. Probably spends most time at redline

And questions..

1) Can someone point me to a good oil "pump" there's no drain so the oil must come out the dipstick.
2) When to switch to synthetic.
3) At that point is Amsoil M/C oil okay (AMF)
4) Is it okay to run non synthetic car oil until I switch to synthetic ?
5) And last, would you recommend 10w-40 ? Would 15-50 or 20-50 be better.

Thanks in advance, I appreciate all the help.

 

[1 FMF]

for high rpm, it is said thicker isn't always better, and I kind of believe that so I wouldn't be too quick to start using a 50 weight oil.
I remember reading here about a 4-stroke watercraft, different brand though I think, that UOA was showing very high fuel % in the oil. In that case, it's a good idea to change oil frequently, and maybe even use a 50 weight.

Most marine service is done every 50 hours for normal use, and 20-30 hours for severe use.

1) west marine, tempo vacuum oil extractor, ~$30. Container will hold 5 qts at a time, have had mine for 4+ years and has been super reliable.
2) probably anytime after 1st oil change- I don't believe synthetics except for a few to be too different than conventional these days, especially with GF-4 oils requiring better basestock oil and groupIII oil being labeled as synthetic.
4) check what owner's manual or dealer recommends for oil, and see how that compares to car oil. Example is merc 25w-40, we have uoa's here on it and it's nothing special additive-wise.
5) for high rpm use and in weather always 70+, I would also look at monograde 40's, maybe something like valvoline racing sae40, or castrol or chevron 40HD if you're wanting to pick up something quick and cheap. If you plan to do frequent oil changes, 10-20 hours, this might not be a bad way to go. But I have no clue what the kawasaki oil is, so I could be wrong.

 

[wileyE]

Just curious what exactly the owners manual specifies? 10w40 API ?? jaso?? how much does the sump hold?

 

[Dick in Falls Church]

Check your manual, and change the first batch when recommended. You can change to synthetic then, or do it after the next batch.

If AMSOIL hasn't come out with the new 10W-40 boat oil by then, my recommendation would be to use the 15W-40 AME. It has a bit better anti-corrosion additive package than does the 10W-40 (AMO/AMF).

 

[Pablo]

I am curious like wileyE - what exactly does the manual say?

The Amsoil marine 15W-40 may be a great choice, or the 10W-40 MC (MCF) or even the 0W-40 4 stroke or 5W-40 Euro oil or the 10W-30 ACD!

1FMF and the others have also given you some great answers.