Lower unit oil change

[TPD211]

I changed the lower unit oil in my 88 spl. I used Castrol Synthetic oil.<br />I also installed a SST Hydrofoil at the same time.<br />I took the boat out and I gained 50-100 rpm at WOT.<br />It was peaked out at 5000 rpm and now is just at 5100.<br />My top end speed appears to be the same, 28-30 mph. This is on a 22' Lowe Deckboat.<br /><br />Hydrofoil? Synthetic Oil? or just my imagination?

 

[Jack Shellac]

Re: Lower unit oil change

I've never heard of a foil increasing RPM, so that only leaves the oil. Based on the testimonials of some of our members, synthetics do give a higher WOT RPM. It got better--that's what counts. I hate it when I go to a lot of trouble and only make it worse.

 

[rickdb1boat]

Re: Lower unit oil change

I don't know either TPD, but I do know that you had better get those RPM's up at least another 600-800 RPM's before you lug the engine to death. Just a little hint that you are running the engine way below it's potential and hurting it at the same time. Re-pitch the prop if you are sure it's running to full capacity...