[quote="hobot"]
The detergents are a good thing in our blow by engines and will not break loose clots like in old days of putting old non detergent engine on new diet of modern oil package. Best time to use hi detergent is on initial run in to get it out of the system then change after initial heat up. Oil filter keep the passages clear but do nothing for the wear particles size getting through, only new oil or fine bypass filtering does. quote]


If I am to understand you, the best time to change the oil if changing to a muti grade, is to do what the British Army & RAF boys do, flush out all of the old oil with DERV in the oil tank, run on fast tick over for about 10 minutes then drain. This will not of course clear out the caked crud in the Centrifugal crank interior, which can only be accessed by dismantling.

BTW, Isn’t Mobil 1 a fully synthetic oil

Dero,

I am using HPR gas 40 this is readily available and the GAS type oil has extra zinc, to help prevent valve guides drying out on LPG applications. But the extra Zinc is beneficial for flat tappet cams, so it helps with cam wear on Commando's.

Cheers Richard

I prefer either Brad Penn or Silkolene, based upon the recommendations of Frank Diehl, the gentleman who did my restoration. Both of these oils have a ZDDP content in the 1400 PPM range. I also use an NOS Lockhart oil cooler connected via a JAGG oil cooler thermostat. (well WAS NOS until I started using it)

dero wrote:I have heard that diesel eng oil is good if used from new in cars ,I guess the same holds true for bikes .
Have previously been advised to only use 50W .

Diesel oil in the four stroke engines should be avoided, every body knows that the DERV engine produces a lot of blow-by into the engine, hence the large amount of detergents in this oil to cleanse this out, I wouldn’t use it even if it was free.

Bernhard wrote:

dero wrote:I have heard that diesel eng oil is good if used from new in cars ,I guess the same holds true for bikes .
Have previously been advised to only use 50W .

Diesel oil in the four stroke engines should be avoided, every body knows that the DERV engine produces a lot of blow-by into the engine, hence the large amount of detergents in this oil to cleanse this out, I wouldn’t use it even if it was free.

Bold illinformed statement

Its more than ok to run diesel rated oil in our Nortons for a number of reasons.
Especially initial run in/break in to clean up and suspend assembly crap and new surfacing metal dust and unsealed ring blow by. I ran out of the older gooder Mobll One we can get no more half a decade ago so put in Rottela I use in tractor and lawn mower and diesel gen set then looked it up to see if I'd fubbed up to find it a good thing that's become my standard last half decade. Generally I can only find 15-40 grade but that falls in zone of temps our cool running engines like.
I've montiored oil and head and exht temps idle to WILD to know it takes deadly danergous WOT low gear use for many miles to get oil, head and exht temps up to maxium that 50 grade might be a bit better but then again at these red line-ish rpms the oil flow is more than sufficient to keep part surfing on lower drag viscosity. You absolutely can not over heat a Norton sitting in still air in 100'F direct sun shine if just idling as fuel burn so low its the lowest temp running you will ever see and ANY throttle to just barely get rolling will spike temps in seconds up to low normal operating temps but at risk of so slow turning the oil wedge is iffy on the lifters and cam lobes. So in reality what feels like safe easy use can be most damaging.

Though marketed as an engine oil for diesel trucks, Rotella oil has found popularity with motorcyclists as well. The lack of "friction modifiers" in Rotella means they do not interfere with wet clutch operations. (This is called a "shared sump" design, which is unlike automobiles which maintain separate oil reservoirs - one for the engine and one for the transmission). Used oil analysis (UOA) reports on BobIsTheOilGuy.com have shown wear metals levels comparable to oils marketed as motorcycle-specific.

http://en.wikipedia.org/wiki/Shell_Rotella_T

http://www.bobistheoilguy.com/

hobot wrote:You absolutely can not over heat a Norton sitting in still air in 100'F direct sun shine if just idling as fuel burn so low its the lowest temp running you will ever see and ANY throttle to just barely get rolling will spike temps in seconds up to low normal operating temps ...

But you can melt your oil lines to the head (the stock kind), if you let your bike idle after running it hot. My brother had this experience after getting pulled over for a speeding violation, and foolishly did not turn off the bike.

[quote]But you can melt your oil lines to the head (the stock kind), if you let your bike idle after running it hot. My brother had this experience after getting pulled over for a speeding violation, and foolishly did not turn off the bike.[/quote

OK granted a speeding ticket heating then immediately sitting in still air at idle would let heat soak soak though and no oil grade could help that scenario nor oil cooler. Wrapping engine in installation could over heat at ilde too, after a time.

After 'over' heated sports bike spanking runs on my return home at saner 80-90's mph it took about 3 sec for exht, 30 sec for head and 3 min for oil to settle to low cruise normals, EgT 1250, CHT 275, oil tank 165 F. Peels cruise rpm was 3500-4500.

If ya don't get to full temps inside the zn/phos don't form nano-pad layer for start up protection wipe off.