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Changing oil grade in a JP2


frangar

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It’s getting to oil change time and this summers hot weather has got me thinking...

 

I’ve always run my JP on SAE20 as per the manual for temperatures in the range of 32-85F and get a hot oil pressure of 15psi at Tickover to 18-20psi at running speed with an engine temp of 60C. 

 

However the manual says SAE30 above 85F and some days this year the engine room must have been that and higher. 

 

So my question is is the temp stated in the Lister manual for ambient or engine room temp? Is it better to use SAE20 so it circulates better when the engine is cold or SAE30 so it’s not too thin when everything is hot?

 

Or am I indeed overthinking the whole thing and just use either? My stockist does both so availability isn’t an issue. 

 

Any thoughts welcome! 

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This is very interesting - I have a 2LW and the recommended grade of oil is  SAe 30 (API SD/CC) for use throughout the year, however Morris's also produce a Multi-grade SAe 20W-50 (API CC/SF), both seem to produce suitable results for engines with no filters, ie.  allowing solid contaminants to drop into the sump.

 

The SAe 30 reduces the risk of bore glazing, but the multi grade improves cold start circulation.

 

It's the cold start up protection which interests me........

 

This  subject has been aired before and I wonder if manufacturers would have used the multi-grade years ago?.

 

L

 

 

 

 

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With a JP it really depends on if you hand start it or not. We supply our engines initially filled with SAE30  ( API SD/CC) oil. Generally this is fine for all of the electric start JPs we do. However, hand swinging a JP in cold weather is a different thing entirely. If I were you are I would run it on SAE20 if you do hand start it fairly often. If you expect to hand start it in the coldest of winter weather the use of an SAE 10 oil can make the difference between success and failure. Back in the day it was normal to run on 10 weight oil from October to April on the old JPs on a whole range of plant I used to maintain. Back then oil technology was very different and engine oil was far gloopier than now. ( Gloopy: 1960s term for oils reluctant to pour in cold conditions, similarly referred to as p*** in plus 70F conditions ?)

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1 hour ago, steamraiser2 said:

With a JP it really depends on if you hand start it or not. We supply our engines initially filled with SAE30  ( API SD/CC) oil. Generally this is fine for all of the electric start JPs we do. However, hand swinging a JP in cold weather is a different thing entirely. If I were you are I would run it on SAE20 if you do hand start it fairly often. If you expect to hand start it in the coldest of winter weather the use of an SAE 10 oil can make the difference between success and failure. Back in the day it was normal to run on 10 weight oil from October to April on the old JPs on a whole range of plant I used to maintain. Back then oil technology was very different and engine oil was far gloopier than now. ( Gloopy: 1960s term for oils reluctant to pour in cold conditions, similarly referred to as p*** in plus 70F conditions ?)

I’ve got hand & electric start and I do use the hand start especially if it’s been standing a while to pull some oil round. I’ll stick with SAE 20 then.  Thanks for the advice. 

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