Oil change....Synthetic?

NiagaraChillin · **Posted:** Thu Jul 19, 2012 12:43 pm

In addition to my T-Stat, impeller issue (posted under St Louis Dave "How bad did I break it post"), I will prob do an oil change while I am crawling around the engine. Is there any issues with switching to synthetic oil in regards to marine applications? I have the 5.0 in my Sundowner.

Cap'n Morgan · **Posted:** Thu Jul 19, 2012 1:16 pm

Older engine likely did not have synthetic. You can switch, but I would keep straight 30W in it. Just my opinion.

ric · **Posted:** Thu Jul 19, 2012 2:03 pm

What brand, weight? Who the heck really knows BUT the advantages of synthetic oil over dino poop is well documented.

NiagaraChillin · **Posted:** Thu Jul 19, 2012 2:09 pm

Yeah Cap'n, its a 1996 with 137 hours.

Gonna go with Valvoline SAE 5W-30 ric, its what I use in my trucks.

LouC · **Posted:** Thu Jul 19, 2012 3:52 pm

I would not use a 5w30 of any kind in a marine inboard, it will thin out under sustained load. You can see this after you have run on plane and then come back to a hot slow idle. The best oil to use that is easily available for inboards are the HD oils certified for both gas and diesel like Chevron Delo 400, Shell Rotella or Pennzoil Marine. You can also use the Merc 25/40 but I am not convinced its better than Delo, or Rotella. I have use straight 30 and 40 Delo and it does not thin out. Synthetic oil per se has advantages but in a gas inboard application the most important factor is that the oil stays in grade and does not shear down under sustained high rpm use. I use the required 5W/20 in the Chrysler Hemi in my Jeep as required but I'd never use that in a marine inboard.

ric · **Posted:** Thu Jul 19, 2012 4:19 pm

I had oil pressure issues with Rotella in my 3.0. It would fall to like 5-8psi at idle when hot and maybe 40psi cruise. Switched to just a generic brand whatever was on sale oil and it went back to 25-30psi idle, 60 at cruise.

NiagaraChillin · **Posted:** Thu Jul 19, 2012 6:15 pm

Thanks ric, no sooner did I post that did I learn that the W in oil does not stand for water. I still want to switch to synthetic, but I will make sure to use the right kind.

fiznuka · **Posted:** Thu Jul 19, 2012 7:21 pm

Careful when switching to synthetic I have heard of several people that have and now leak oil. I don't think your oil will lose viscosity fast enough to justify the cost. Maybe think about a durablend.

Technologic80 · **Posted:** Sat Jul 21, 2012 5:20 am

5w/30 in ANY marine sterndrive personally insults me. Yes, you can use it in its automotive counterpart just fine, but does your car/truck with the same engine run at 4000RPM's for 20 minutes at a time? The engines are the same, but the applications they are used in are a total 180 from each other!

With that being said, I used to use Amsoils 30w/10w-30 full synthetic in my 5.7l and I experienced low oil pressure alarms after coming off plane all of the time. Switched to 15w/40 and never had a problem again.

I now use Chevron Delo 15w/40 in all of my marine engines. Never have any oil pressure problems. On plane, Im at 60-70psi, coming off plane with an engine at temp and it never goes below 20-30psi.

DO NOT USE 5w/30.

NiagaraChillin · **Posted:** Sat Jul 21, 2012 11:23 am

Thanks for the tip Technologic, I will def not use the 5w30. Next question is how do you get a drain pan under the engine? Is there a special pan made for boats?

txvista · **Posted:** Sat Jul 21, 2012 11:42 am

I just used this pump this week. I borrowed aguyindallas'.

http://www.westmarine.com/webapp/wcs/st ... ArbxI6yW24

NiagaraChillin · **Posted:** Sat Jul 21, 2012 12:38 pm

Now that is pretty nifty....I can see that in my future, but $144.00 tho? Ouch.... (I know, if I didn't wanna spend $$$$, I would have taken up rock collecting instead of owning a boat) :lol:

LouC · **Posted:** Sat Jul 21, 2012 1:03 pm

Look a the dipstick tube, if you see what looks like garden hose threads on it you want a vaccum pump that can use a garden hose attachment, it's much faster than the little tube down the dipstick tube method. I use the Topsider which is a well made metal pump that holds a lot of oil, and I adapted a garden hose fitting to it. You can use either an electric pump or a vaccum one, the good electrics are expensive, the good vacu pumps are a good deal less I forgot how much I paid for it. I also use it to suck differential oil and trans fluid out on my Jeeps, makes changing fluids when you don't have a drain plug much easier.

Make sure you can get at the filter. Is that a Ford engine, if so, the filter is up front on the port side (but right side as you face the engine). Make sure you can get a strap wrench on it, if not, try to find a cap wrench that fits. I have the Chevy 4.3 and just like every other Chev small block the oil filter is up against the bellhousing way in the back. Fortunately I can get at it with the cap wrench.

As far as oils, I'd use straight weight 30 Chevron Delo 400, Shell Rotella T or Pennzoil Marine. You can use the Delo in 15/40 if you have cold temps but I have never had any trouble starting my old 88 with straight 30 or even 40 Delo.

If the motor has be run on conventional oil I don't see a big need to change to syn oil. The advantages of syn oil per se are mostly at the temperature extremes of very cold and very hot. Marine engines aren't used when its cold unless it's commercial use and they are not supposed to get hotter than 175-180 water temp anyway so oil temps should not be that high, a good HD single weight oil is more than adequate to cope with those conditions. It's hard to find a syn single weight oil in the correct viscosity. Volvo used to sell a syn straight 30 but no longer. You would be fine with the oil we recommended.

NiagaraChillin · **Posted:** Sat Jul 21, 2012 6:56 pm

Okay, after weighing all the advice here, and doing a little research on line, the winner is..........Shell Rotella T 15W-40.

Thanks all for the advice, now to get me one of those cool oil-thru-the-dipstick tube-pumps....

taz42169 · **Posted:** Sun Jul 22, 2012 5:39 am

B.O.A.T.....Break Out Another Thousand! Welcome to a big boy toy.. LOL

:shock:

www.iFourWinns.com

Oil change....Synthetic?

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