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New Proud Owner of an Onan JC


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  #11  
Old 10-03-2017, 06:39:49 PM
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Default Re: New proud owner of a JC

Quote:
Originally Posted by Handyhiker1 View Post
I have a JC that has a few thousand hours from what I can tell and with 15w40 the oil pressure guage burys itself at start up. If it were me with that few hours, the 5w40 would be a better choice.
I agree with Handyhiker1 about the 15-40 being a bit heavy especially in Georgia and winter weather. I would not run a synthetic such as the Rotella 5-40... YET, until you get some hours on the set. Best to put some straight 30wt or 10-30 and run it for 1-5 hours with a load then drain it and change the filter.
I would still wait for a while before you put full synthetic for such a low hour engine. Older engines that weren't designed initially for running synthetic from day one, should be run on conventional oil until FULLY broken in before switching to full synthetic oil. I waited a year with several extended runs on my low hour JB before switching to Rotella-T, 5-40 full synthetic. If you switch too soon, I have heard that an older engine type can then burn oil.
Just my opinion.
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  #12  
Old 10-03-2017, 07:34:55 PM
Leon N. Leon N. is offline
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Default Re: New proud owner of a JC

Motörhead what do you mean by saying the oil pressure gauge burys itself at startup? In all my 47 plus years of running my JB I have never seen the oil pressure exceed 50 pounds. I have been using 5W20 full synthetic all year ever since it became available. My cranking oil pressure is the same as the running oil pressure @ 45 psi.
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  #13  
Old 10-03-2017, 07:43:35 PM
Handyhiker1 Handyhiker1 is offline
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Default Re: New proud owner of a JC

Leon, that is my JC that burys the guage at start up and for the first 5-10 minutes with 15w40. I can't remember what the guage goes to but it is a factory guage. After it warms up it drops but again I don't remember the pressure but it is about 3/4 on the guage.
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Old 10-03-2017, 07:50:15 PM
MBB MBB is offline
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Default Re: New proud owner of a JC

Here is some info on your unit.
Attached Files
File Type: pdf 15JCL1681AB.pdf (26.0 KB, 23 views)
File Type: pdf 612-5559.pdf (284.5 KB, 19 views)
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Old 10-03-2017, 08:06:59 PM
Leon N. Leon N. is offline
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Default Re: New proud owner of a JC

Handyhiker1 if you mean your oil pressure is pegging the gauge on start up, that is not a good situation in my opinion. You could damage your oil pump! Problem is you do not know how high it is. There are several things that could cause this. There is nothing gained by using hi viscosity oil. What is most important is the film strength and that oil is getting to all the places, Right From The Get Go. If not as Onan once told me, 90% of the wear occurs in the first 15 minutes of operation.
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Old 10-03-2017, 08:30:00 PM
Handyhiker1 Handyhiker1 is offline
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Default Re: New proud owner of a JC

Leon, I totaly agree with you. When I got my JC this is the oil I just happen to have on hand. I used it but had no idea it would cause this to happen. I plan on changing it to a 5w30 as soon as I start working on the JC again. It has just been on the back burner for now as other projects have come up. I did put it on a cart and got a panel mounted but have not had it running for some time.
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Old 10-03-2017, 08:47:25 PM
Leon N. Leon N. is offline
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Default Re: New proud owner of a JC

Handyhiker1 well I feel a bit better. You know, there are several different opinions about what oil to use and what viscosity to select. All I can say is that I came to the realization after several years concerned about the proper libricating of my JB which sits cold soaked at or below zero sometimes that "thinner (low viscosity) is better" since the advent of synthetics which have excellent film strength at high temperatures as well as good cold flow properties. Just look at what the newer cars require. For example, our little 4 cylinder Honda requires 5W20 full synthetic Summer and Winter. Same goes for my newer Camry.
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Old 10-04-2017, 10:49:36 AM
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Default Re: New proud owner of a JC

If this unit has lived its entire life on NG, then I would be suspicious of the diaphragm in the fuel pump. It could likely be compromised.
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Old 10-04-2017, 11:50:22 AM
Handyhiker1 Handyhiker1 is offline
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Default Re: New proud owner of a JC

It is kind of funny how many JCs are coming up for sale right now. Seems like it goes in a cycle, for a while it is other sizes and then changes.
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  #20  
Old 10-04-2017, 01:50:45 PM
Leon N. Leon N. is offline
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Default Re: New proud owner of a JC

Just curious but why would you be suspicious of the diaphragm in the fuel pump? My JB is of the tri-fuel design and the fuel pump remains in tact with no oil leaks so far. It has never operated on gasoline, hopefully never.
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