gferdon

Hydrocruiser,

Just curious to know what type boat you run your 350 mags in? Also, drives, props, speeds, etc. Your comments were well written and made sense. As you are no doubt aware, the subject of oil choices and change intervals is varied and sometimes confusing on the board. Thanks for the input.

G-

Hydrocruiser

It's a Wellcraft Nova ST 28' LOA
Stock 350 Mags
Twin counter-rotating Alpha drives- Change with Merc Hi Perf Gear Lube every 25 hours
21 Pitch Hydromotive "Bravo" Turbo Props
64 MPH

I started using conventional oil then switched to Mobil-1 and later to Amsoil. This season tried Royal Purple. In order to go to extended intervals I personally only would do that with Royal Purple, Amsoil Series 2000 or Redline. They are designed and promoted by the manufacturer for going beyond recommended changes. Royal Purple is becoming my favorite as it has increased top speed by 2 MPH. (I may try RP gear lube in my drives.) That has to be from less friction. All performance magazines show a HP gain with Royal Purple. About 90% of oils have moly in them but RP and Redline have larger amounts. Amsoil does not use moly they are into calcium additives. Here is an article on moly. Studies have shown much less "blow-by" in oils using moly. Blow-by is gas blowing by the rings and getting into the oil. That will wreck an engine faster than anything because it destroys the oil. If you have a blower you should always smell the oil for gasoline from blow-by routinely. A new filter may get some of the gas out, but if it smells like a lot gas fumes coming off it's time for a change no matter how many hours. RP and Redline are excellent for blower engines. They form a better seal in any engine.

http://www.bobistheoilguy.com/moly.html

Redline, RP and Amsoil offer repair warranties if your machinery fails do to an oil related issue. The racing oils are not guaranteed.

gferdon

Thanks for the detailed info, I have another question. Do you have oil temp gauges on your Nova (nice looking rig BTW) and, if so, what temps do you run. Mine seem very high, example: 3000 rpm cruise = 230 deg. F WOT = 260 deg F. Seems I read somewhere that you should not run conventional oil in excess of 260 deg. for over 5 minutes. I have a buddy that has a 525 MPI and never gets higher than 210, even at WOT! I am going to try the Royal Purple oil but have another problem. I never have been able to get the advertised amount of oil to drain out of the engines. Manual says that the engines hold 6 qts, most I have seen drain out is 4 qts. I have used both the drain tubes and have tried pumping out thru the dipstick...same result. Any ideas? Thanks again for the reply.

GF

Hydrocruiser

They say 195-230 degrees is optimal. Anything significantly above that and an oil cooler installation or upgrade might be worth a look. Royal Purple runs 10-20 degrees cooler for me though I run 10w40. A lighter weight oil has a larger volume of flow and better cooling and this oil holds it's viscosity very well. A 20w50 conventional in 20 hours is lucky if it is a 5w30 or 40 from heat and shear. Conventional oils will loose viscosity index under heat more so than synthetic oils.

As far as getting your oil out some boats like mine need to be on land on a platform to fully drain them and others are set up for complete drains in the water. You may be volatilizing oil if you are running too hot. The oil may be thickening and loosing volume. That's something to watch as sludge can form if that's the case. Try using an engine flush before your next change. Try a good premium synthetic and see how you do. Royal Purple 10w40 or 15w40/ Amsoil Series 2000 20w50/ or Redline 15w50. Mobil-1 15w 50 is a good choice too if you change every 25 hours or so. The others can go twice the distance with a filter change and top off at 20 hours.

Here is a good article on both conventionals and synthetics:

http://www.vtr.org/maintain/oil-overview.html