Thoughts on this industry change to 5w30

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Nov 22, 2017
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Location
Ohio
Attached is a screenshot of an advisory from PCM (the engines in Nautique boats). They are suggesting the 6.0L and some other engines switch to 5w30 Dexos 2 instead of 15w40. I know that Ilmor and Indmar are also saying run 5w30 in some of their newer engines.

I have a LS1 Engine and it's is similar to an 6L internally. I've always struggled running 15w40 and 15w50 since I got this thing . It's certainly not a run of the mill 5.7L Chevy Gen 1. I plan to keep my boat another 20 years and 2000 more hours so engine wear is a bid deal to me.

I know old school is run thick oil to handle fuel dilution and stress but I wonder how much stress my boat really sees pulling skiers at 3000-3500 RPM - this thing has 375 HP and it doesn't seem like it's breaking a sweat.

I'm still running PB 15w40, but Is there something special about the Dexos that is driving this decision ?

PS - what do you think of Rotella Gas Truck 5w30 in a boat ? Seems thicker than most. https://shell-livedocs.com/data/published/en/86da4bf5-68c8-4676-bbe7-a2d42cc13ba7.pdf

PCM Oil.jpg
 
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Well changing your oil every 30-50 hrs or 120 days is going to be fun.

I would probably meet in the middle with a 5w40 and do 100hr+ oil changes.
 
I don't think fuel dilution would be an issue in modern port-injected engines like the LS1.
Mine always worked fine with 5w30 used in track days. In that environment, I was continually cycling the engine from 3000-5500 rpm.
3000-4000 rpm pulling skiers doesn't sound like it will overwork a 5w30.
I tended to choose oils that were on the stout side of the 30 grade, and always with 3.5 HTHS.
Rotella Gas Truck 5w30 may be good since it's formulated for trucks and has good oxidation resistance.
 
Just going off my friends with boats. Both friends have 600k+ with smallest being 45ft IIRC. Both are gas and from what I can see the PITA it is to do basic maintenance on the gas engines pays off in the long run. In the NorthEast 0-40 is a good compromise with short seasons due to winter. I would think Ohio seasons relatively similar. 100 engine hours is a good benchmark depending how hard you drive it. Have you changed the oil in your engine? How hard is it? Some engines in boats are just horrendous to get to.
 
I typically change every 40-60 hours anyway at the end of each season. It takes 15 minutes to change because it's a straight inboard and I trailer it.

I just thought it odd the lower viscosity. I have wanted to run a stout 5w30 but haven't because everyone typically runs 15W40. If it was a standard 350 I wouldn't question it. The Corvette engine is what has me wondering.
 
On my boat with a 4.3 GM engine the oil gets pumped out through the dipstick tube, so not hard to do. I wouldn't use oil that thin unless I were going to change it more often.
 
Wow, Im clueless, manufacturer is supposed to know best. I dont know if I could do it and go to a 5/30 but unusual for the service advisory so something maybe up and might be worth listening too. Just dont see how a difference from 40 to 30 could matter to the point that an advisory would come out. I suspect its needing the Dexos more then the 30.

One thing for sure your 375 HP engine has a lot less stress then a smaller engine.
 
inboards typically run 140 to160F thermostats, so the oil does not get as hot as in cars and trucks with 200 degree thermostats. Lighter oil will have more throw off from rods to cool pistons and dissipate heat from bearings. I don't think you will see an issue.

Rod
 
Originally Posted by ragtoplvr
inboards typically run 140 to160F thermostats, so the oil does not get as hot as in cars and trucks with 200 degree thermostats. Lighter oil will have more throw off from rods to cool pistons and dissipate heat from bearings. I don't think you will see an issue.

Rod


True, but they do run under a constant load and high throttle positions unlike in cars and trucks.
 
Originally Posted by ragtoplvr
inboards typically run 140 to160F thermostats, so the oil does not get as hot as in cars and trucks with 200 degree thermostats. Lighter oil will have more throw off from rods to cool pistons and dissipate heat from bearings. I don't think you will see an issue.

Rod

Don't confuse water temps with oil temps. the 160 Thermostat is to meet coast guard regulations. The oil on these engines runs far hotter than in cars due to the load. It would be like pulling a 400o lb trailer with your truck at wide open throttle all day long
 
Originally Posted by Bluestream
Originally Posted by ragtoplvr
inboards typically run 140 to160F thermostats, so the oil does not get as hot as in cars and trucks with 200 degree thermostats. Lighter oil will have more throw off from rods to cool pistons and dissipate heat from bearings. I don't think you will see an issue.

Rod

Don't confuse water temps with oil temps. the 160 Thermostat is to meet coast guard regulations. The oil on these engines runs far hotter than in cars due to the load. It would be like pulling a 400o lb trailer with your truck at wide open throttle all day long


True = there is no correlation of oil and water temperatures.

False = the 160 Thermostat is to meet coast guard regulations.

________

Marine engines have 160 degree thermostats to prevent salt from crystalizing inside of the engine. 160 degrees is that magic number where this can start to occur.

(this is from a site discussing the benefits of closed cooling in marine engines)
"
Besides exposure to corrosive materials in the water, raw-water cooled engines suffered from another major drawback. They had a thermostat, just like all engines, but it was regulated at 145-150° F. This was done to minimize the possibility that salt in the salt water would separate out and crystallize inside the engine's cooling passages, with 160°F being the critical turning point for this to occur. "
 
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i did a little more reading and from what I can tell they are doing the lower viscosity on some of the new PCM engines due to problems with failing oil pumps. And also for the direct injection engines.

I'm still sticking to my 15w40 ... If it aint broke, don't fix it.
 
It mentioned direct injection … perhaps they want the Dexos 1.2 for LSPI concerns … and a big portion of 5w30's carry the license (pretty much that and 0w20)

Guess we were typing at the same time … might want a lube that lowers calcium by use of magnesium
 
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you know I think you are on to something with Pre Ignition issues in DI engines. I wonder if they just said 5w30 to keep the recomendation consistent with all there new engines. The old engines they mention to say on 15w40 haven't been made in some time
 
I'm not sure how similar the blocks and oiling systems of the boat motors are to the car and truck engine but in 2014 GM changed the oiling system of the the 5.3 and 6.2 LS engines to run at 70 psi pressure, up from about 40 psi. Perhaps this figured in their decision?
 
Originally Posted by Skier
i did a little more reading and from what I can tell they are doing the lower viscosity on some of the new PCM engines due to problems with failing oil pumps. And also for the direct injection engines.

I'm still sticking to my 15w40 ... If it aint broke, don't fix it.

Originally Posted by Skier
i did a little more reading and from what I can tell they are doing the lower viscosity on some of the new PCM engines due to problems with failing oil pumps. And also for the direct injection engines.

I'm still sticking to my 15w40 ... If it aint broke, don't fix it.

The pump is designed to produce 70 psi at the rear at the top of the driver's side head where the pressure gage is mounted on the intake manifold. The pressure at the pump where the oil enters the block is higher than 70 psi. If you use 15w40 some the oil pressure will be even higher and the pressure relief spring in the pump will dump some oil back into the pan. I'll post a link to show the presence of this bypass spring. Certainly the direct injection issue is a concern as well.
Here is the link to show you where this spring is. I'm not advocating any change, just showing how the pump will be bypassing oil back to the pan. Keep in mind the pre-2014 LS engines were set for 40 psi at the manifold so the issue wasn't as important. The only gray area would be the 6.0 liter engines. They carried on past 2014 without the update. Not sure what they use now for a pressure. Good luck with you engine.
 
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The last year for the 6.0 in a vehicle was 2010 except for the hybrid which made it to 2012 but there are still 6.0 engines for the boats. The 6.0 never did get converted to Gen V and so did not get the 70 psi oil pump. So, its a bit puzzling on why they asked for a change back to 5w30 on the 6.0. Also, as far as I can tell the PCM 6 liter engines are still port injected if the website is up to date.

http://pcmengines.com/engines/
 
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Originally Posted by Snagglefoot
The only gray area would be the 6.0 liter engines. They carried on past 2014 without the update. Not sure what they use now for a pressure. Good luck with your engine.


Update: The last 6.0 installed in a truck was in 2012.

I realize now the 6.0 boat engines are still being produced. I don't thing they were updated to Gen V status, however. Anyone have the scoop on that?
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Yeah it's all over the board. Ilmor is suggesting 15w40 Rotella for their 6L and 5w30 for the other engines

Marine Power is suggesting 15w40 for all the Gen IV stuff that is not supercharged and 5w30 Dexos Gen 2 for all the Gen V DI engines

my Gen III LS1 is running about 35-40 PSI at Idle and 60 all full throttle. I guess that makes sense about the higher flow pumps needing lower viscosity.

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