Oil rec water pump Honda GX390 Penrite 30 vs 15w50

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Which oil Penrite SAE 30 or Penrite 15w50 for Honda GX390 in ?
Penrite SAE30
Penrite 15W50
I have been using Penrite SAE30 (mineral) in all of my stationary motors, but on the last oil change of the water pump (Honda GX390) i noted some flecks of brass/copper. Looking at Honda's manual there oil chart only covers a0w30 and straight SAE30 up to 40'C (104'F). I regularly have to run this pump at the limit of this oil chart and beyond; 35-44'C, but some days is only ~25'C (77'F). This pump runs for a minimum of 3 hours per run and during emergencies (Bushfires/wild fires) has cope with multiple runs per day. Is the 15W50 to 'thick' for the cooler days?

I'm looking at running the Penrite 10 TENTHS RACING 15W-50 (PAO ESTER) as i have ~4 liters leftover from a motorcycle which is now sold... (Prob overkill as 2200+ ZDDP package in a full synthetic)

Should i continue running the Penrite SAE30 (Mineral) or give the Penrite 15W50 full synthetic a go?

I know there are a lot of threads re running the 15W50 in these 'types' of engines (air-cooled) during hot condition and the fact B&S are now using this weight oil in commercial applications would add to the confidence of giving the Penrite 15W50 a go...

BUT, my concern is the Honda might have tighter tolerances and not like the heavier weight oil on the cooler days / start-up...

Regards,
Dewy.
 
I run a plain jane 15W-40 HDEO (diesel engine truck oil) in my GX390 generator.

I think it is either Supertech or TSC Traveler, 15W-40 (it's been in to long to remember)

Synthetic is overkill, but then again when fighting fires - who cares about the oil cost?
 
I would use 15w50 given the conditions. 25*C isn't cold either. You'll be fine.
smile.gif


The key is to make certain they are:
1. Topped off at all times.
2. Sitting on level ground.
3. Changed at the correct intervals.
 
I've not got a Honda stationary engine, but I use to run Castrol Edge 10W60 in my Honda motorcycles (CBR) and it worked well.

I think the Penrite 15W50 full synthetic should work fine in an air cooled engine. I've also used GTX 20W50 in my B&S mower without problem, it specc'd SAE 30 but I didn't have any on hand.
 
My vote is for Penrite 15w50. Thinner at starting than 30, thicker at operating temp than 30. The 15w50 is made to withstand harsher conditions than the 30. Anymore, most small gas engine manufacturers are recommending a 15w50 or 20w50 for hotter environments like yours.
 
Thanks for the advice... I think I’ll run the 15w50 just to see if the oil has less contamination than the straight 30...

Always run the pump at 3000rpm so will be interesting if needs more throttle for the same load.
 
Originally Posted By: Dewy
Thanks for the advice... I think I’ll run the 15w50 just to see if the oil has less contamination than the straight 30...

Always run the pump at 3000rpm so will be interesting if needs more throttle for the same load.
Like to hear how it turns out. I doubt you will need more throttle. It will not be as thick at start up, so it will never see thickness as it did with 30 weight. When its at operating temps., the oil is almost runs like water, the 50 will be a little thicker, but still tons thinner than even when you were at start up.
 
Just for info the 15w50 has a Viscosity, Kinematic, cSt at 40°C of 114, where as the SAE30 has Viscosity, Kinematic, cSt at 40°C of 90; so the 15w50 will be thicker throughout the temp range... Its this start up thickness i was worried about. Once the air-cooled engine is up to temp the Viscosity, Kinematic, cSt at 100°C 17.5 and 10 for the SAE30, but expect oil temp will go higher in the hot weather in Australia..
 
If I were to start my mower with PYB 10w30 on a 70 degree day in my area, the oil would be a whooping 180, and it still holding together. So I wouldn't worry about your 114.
 
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