Pesky Varmint

460 hours and 6 years on two 575SCi's bone stock.

Part of yearly maintenance is to check the oil in the little
drive unit for the diaphragm fuel "pre" pumps at the front
of the engine by the raw water pumps (else they run dry
and ruin said pump).

The head gaskets suck. You're on borrowed time with them.
Mine just failed leakdown specs at 450 hours so I refreshed the heads anyway.

I have the early blowers, those are the reliable ones (although
I did have to have one blower rebuilt when the boat was two years old, the blower was consuming oil). And that reminded me, keep tabs on blower oil. There are front and rear reservoirs.

In general I'm pretty happy with them.

Pesky Varmint

kjm5125

I mainly run 89 octane with no issues and the engines run strong. Contacted Merc. on the octane issue and they said the engines will be fine at 89 octane. Regardless, I add Supreme 130 octane boost when using 89.

Steve Zuckerman

Very reliable stock with the above caveats (****ty head gaskets, blowers should be rebuilt at 100 hrs, mechanical fuel pump reservoir issue is common to several blue Mercs).
Easily modifiable for more HP. Likes more boost and intercooling. MEFI 3 is easily reprogrammed.
I agree the 525 is also a good motor, but the computer is to my knowledge unhackable, making mods difficult. If you are leaving it stock, OK. But I think horespower is like t-ts, you'll rarely hear someone say "she has too much" .........
Regards,
Steve