oil changes?
 

at what time intervals are you changing your oil, i was originally gonna change at the fifty hour mark, but i may go less than that, it is on a 7.4L

Re: oil changes?
 

It depends on how you are running it. Hard every 20 hrs. Average 30 maybe 40, thats pushing it.

Re: oil changes?
 

Change it when it starts to get dark, don't let it get black. 50 hours is way too much.

Re: oil changes?
 

Do an Oil Analysis....That will tell you if you need to change more often or less....Will save you tons in the long run...$15 will usually get you a good test. Results usually in 2-3 days.

BH

Re: oil changes?
 

I've always changed mine every 20 hrs.

Re: oil changes?
 

Myself 20 hrs regardless of how it was ran. Also use a good oil and filter, its worth it in the long run.

Re: oil changes?
 

well, i've got 27 hrs on mercruiser oil and filter, on a 7.4 L

Re: oil changes?
 

You should be fine, but it's probably time.

I love my HO's. They actually tell me when to change it. They don't burn a drop of oil until between 25 - 30 hours. Then when I see the oil level start to drop I know it's time.

Re: oil changes?
 

Every engine and application has a different maximum frequency change and a minimum. The minimum is usually 20 hrs on higher HP engines especially those with blowers. So if you change every 20 hrs no matter what engine you have and use a premium conventional or synthetic oil and a quality filter such as a Mobil-1; Amsoil; Baldwin or A/C Duraguard you are being extra careful and are less likely to experience premature wear or an oil failure.

A good perspective might be comparing service hours in cars to boats. Cars usually ought have an oil change every 3,000 miles. If you average a speed of 45 MPH that's about 65 hours between changes. But the service duty in a car is light to moderate at best in most cases whereas a boat is considered high to severe duty.

If you use a premium synthetic (Amsoil 20w50 Severe Duty Series 2000; Royal Purple 20w50; Redline 20w50 all at $ 6.00 to $ 8.00/qt) and are comfortable with extended oil changes you would be fine going 40 hours but changing the filter every 20 hours and topping off. I have enough faith in these products to go that route as long as the fliter is a premium filter such as a Mobil-1; Amsoil or Baldwin or Wix plus I now use a magnet on the filter too. I think the time is here to consider this. I am doing this myself now on my 350 Magnum's. I did an oil test on each engine after 25 hours and running a new Mobil-1 filter and topping off, for an hour before sending the sample, they came back as basically being "new oil" data results with no contamination. No water, no acids, no metals. I was running Royal Purple. The "moly" in the oil was shown present as I knew it would be. I am finding that the more I use Royal Purple or Redline the more I like it. Redline and RP hold up best in HTHP tests across the board due to the moly additive. So I will plan to change the oil at 50 hours next but send a sample before at say 40 hrs just to see what was in there.

I like the idea of using a premium oil and oil filter and going the season with only one change. I go by test results. If the oil came back in "new quality" after 25 hours and granted an hour through the new Mobil-1 filter. Then that's all you need to do.

Mercedes Benz in it's S-55 AMG 496 HP twin screw blower motors says to go 15,000 between changes using Mobil-1 0w40 oil. At an average speed of 45 MPH that's over 300 hours. Porsche also says to go 7,500 in their Twin Turbos using Mobil-1 10w30 and that's around 150 hours. You don't have to change filters or top off either. If you use a premium synthetic like Amsoil 20w50 Severe Duty you can go twice the frequency with a premium filter change in-between.

The time is here and I am doing it. I analyzed my 20w50 conventional oil after 25 hours last year and it was broken down to a 5w40 and had metal in it. Test your conventional to a synthetic for a few bucks and you will see similar results.

I am doing this in 350 cubic inch GM engines. I would be ok in a 496 or 525 as well. I would not extend in marine blower applications because they run "fat" and gas gets into the oil regularly from blow-by. That's got to be a 20 hour change no matter what you use.

As always. Use what you like and change when you like.

Re: oil changes?
 

how about the drive oil, what r the intervals for it and on a bravo one, i don't need any special tools do i? just crack the vent till it starts running out and then the resivoir all the way, right?

Re: oil changes?
 

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-

Re: oil changes?
 

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.

Re: oil changes?
 

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

Re: oil changes?
 

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