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Engine oil for AQ130C

am_dew

Advanced Contributor
"Every year I ponder whether I

"Every year I ponder whether I should use straight 30W or 10W-30 oil in my AQ130C? Most of my boating is done in warm weather (Sacramento, CA area) with air temps often being over 90 F and as high as the low 100's. Occaisionally I will do some fishing in the mountains with cold temps (30's and 40's) in the morning.

A mechanic once told me to just use straight 30W. The V/P manual says to use 10W-30 or 20W-40. I've read some comments about using 10W-30 in a marine engine which suggest that multi-weight oils can break down in a hard working marine engine.

What do you other AQ130C owners out there use in your engine?"
 
"Bob, I sold my AQ130 about 3

"Bob, I sold my AQ130 about 3 years ago, but I have been using occasionally SAE 10W-40 and mostly SAE 15W-40 in all Volvo-GM-Ford marine engines I have owned. The reason for me not using SAE 10W-30 is to prevent the oil pressure from dropping too much (especially at lower RPM) when the engine has been running hard.

You can certainly use monograde 30W with no adverse effects. The only difference is that it may be a bit harder for the starter to crank the engine in cold weather."
 
Thanks El. Just curious...why

Thanks El. Just curious...why might the oil pressure drop after running hard while using 10W-30? This concerns me since I do run at higher RPMS a lot.
 
"Bob, mineral oils do not have

"Bob, mineral oils do not have much viscosity by themselves, and viscosity diminishes with temperature: the higher the temperature, the lower the viscosity. Therefore, oil manufacturers need to include additives to maintain oil viscosity with higher temperatures. Also, multigrade oils are being used because they have a number of additives that make them sufficiently thin to remain fluid at low temperatures and thick enough to keep the oil pressure at higher temperatures. However, even multigrades have limitations. If you have a pressure gauge installed in your boat's instrument board, you will notice that when you start the engine (cold) the oil pressure is high at a given number of RPM, and when the engine has warmed up the oil pressure dimishes (again, viscosity goes down when the temperature increases). In some engines, a 10W-30 oil may perform well say in a car, but in a boat the oil usually becomes hotter because of the operating conditions, and the oil viscosity may become too low to maintain an adequate pressure. Since the oil pump is driven by the engine, the lower the RPM the less volume of oil it pumps; and if the oil is too thin, the pump may not be able to maintain an adequate pressure in main and rod bearings.

As I said, I have found that with 10W-30, the oil pressure may be too low at lower RPM (say 15-20 psi, sometimes even less) after having run at full throttle for awhile, and this can lead to crankshaft/bearing damage (metal to metal contact) if you suddenly decide to accelerate; also, the oil pressure at full RPM could be as low as 45 psi. I found that with 15W-40 the oil pressure seldom (if ever) goes below 35 psi at lower RPM, keeping a healthy 55-65 psi at higher RPM.

The only drawback I can find is that with higher viscosity oil there is a marginally higher fuel consumption, which I believe is cheap insurance when considering that running with low oil pressure can lead to ruining a crankshaft."
 
"Wow...great info El...thanks

"Wow...great info El...thanks very much! You've convinced me that I should use 15W-40 in my upcoming oil change, which did not get done last Fall as it should have. My only concern (and I'm probably thinking waaay too much into this!) is that since this engine has had only either straight 30W or 10W-30 in it during it's 200 hours or so of service, will the higher oil pressure using 15W-40 cause any oil seals to be more prone to leaking? Or is the oil pressure while using 15W-40 still well within the "OK" range (or not any higher than when oil pressure is optimal using the 30W oils) where that is not a concern? Again, thanks a lot for your valuable information and insights."
 
"Bob, every engine oil pump ha

"Bob, every engine oil pump has (or should have) a relief valve installed to deal with potential overpressure. In any case, if you look at the Volvo instructions for the AQ130, they recommend 10W-40; and Seloc recommends 10W-30 and 20W-40 for the same engine. Which one to choose? Well, as I said I have found the 15W-40 to be a good all-around oil, with the added advantage of its higher content of detergent additives, as it is also formulated for diesel engines.

And if you are not confused by now, here is something else: my current engine (a Chevy 350 ex AQ311) needs, as per Volvo's instructions, 10W-30; and as per Seloc, 10W-40; but if you use the same engine in a Mercruiser application, the oil that Mercruiser recommends is 25W-40 (although, unlike Mercruisers, some Volvo versions of the GM350 normally have an oil cooler).

Clear as mud?

In any case, remember that the recommended oil pressure range for your engine is (according to Seloc) 35 to 85 psi. As long as the oil you use keeps the pressure within that range, you are fine."
 
'Clear as mud?'

Per


'Clear as mud?'

Perhaps the most interesting 'statement' You made.
Personally I used Shell Nautilus 15W-40 the last years. But perhaps the most important is to use a high quality oil that does NOT leave a layer of 'mud' at the bottom of Your oil pan!
 
"OK, Napa 15W-40 (made by

"OK, Napa 15W-40 (made by Valvoline, I understand) it will be for the upcoming oil change!

Now for my next, mostly off topic, question:

Should I stick with either 10W-30 or straight 30W for the 270 outdrive oil change, or will the 15W-40 be OK for it? I've always used whatever I put in the engine.

P.S. My boat only has an "idiot light" for oil pressure."
 
"Those drives with that engine

"Those drives with that engine are almot bulletproof and works with next to whatever You put into it. The 'old' recomendation:Same as engine, was more of convenience for the owner than as a technical requirement. Ther is one thing to take into considderation, and that is the power loss. The thicker the oil, the more power loss due to 'resistance' in the oil pomp (impeller). I did some tests some years ago with a 24ft and twin 130's. The difference of running 15W-40 and Mobil 1 (5W-40) wa almost 10% both in speed and rpm in watertemps aound 15C. However the Mobil 1 made some hard shifting noises! As a general use I ran all drives on Hi-Vis and Ultra HPF. For drives that was run hard during the season (V8 and diesels) on engine oils, I was never sure if I drained the toilet tank or the drive from the smell and color of the oil!"
 
Thanks Morten. I think I'l

Thanks Morten. I think I'll stick with straight 30W for the outdrive. Seems to do OK given that it's 35 years old and still running strong (knock on wood).
 
"Good move, Bob. As they say:

"Good move, Bob. As they say: if it ain't broke, don't fix it.
biggrin.gif


BTW, I have been using all along 10W-30 for the outdrive (280) and have never experienced any problems."
 
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