Changing oil types.

[Interpol2471]

Hi all, I am running on Rotella X at present but want to change to Silkolene as suggested by Richard. What is the best way to change oil people have found, do you have to drain every last drop out or can you run it low and then just top up with the new oil. I cant see much of a problem running low and then adding some new oil and re-draining a bit before fully topping up due to the oil just being burnt. What does anyone else think or KNOW :?: Thanks

[Malc]

I had this job on all the Derbyshire police bikes as Silkolene won the contract to supply fleet.If possible run the oil tank low and draw out as much remaining oil as possible using a fork oil syringe or similar. (Trying to remove the oil feed plug with the gauze filter on is fiddly as the chain gaiter is in the way and not all the oil will drain anyway)Refill tank with Silkolene and undo oil pump bleed screw until the oil runs red. Check there are no air bubbles in the pipe, tighten bleed screw, job done.MalcA note on the Silkolene SRG75 gear oil, the 2 long term test bikes being run on this oil were both written off after accident damage, couldn't have been the 'force' dog that ran out and caused the accidents as with the cars, so it must have been the oil!

[Interpol2471]

Thank you I will do that, I guess getting as much oil out is the order of the day.

[dave perry]

Hi Chaps, in my usual hamfisted way I have just topped up the tank with Silkolene; it was about half full at the time. Graham is trying to get me a good price (goodish !) on a 20l barrel. I will let you know how I get on, Regards dp

[Interpol2471]

I guess you had half a tank of your old oil, did it mix ok?

[Malc]

I dont think it will be a problem not having drained the tank before changing from one oil to the other. I would consider it more precautionary. I remember Richard N telling me that tests were done at Midwest/Diamond when the oils were changed with no ill effect.On the police bikes, Silkolene said not to change back to mineral because of the risk of any engine problems, but they would have to say that to cover themselves against any claims.There was no noticeable difference between running the police bikes on either oil apart from the cost.Eventually, as the fleet became mixed again (Derbyshire was the only force to switch wholly to Nortons)it was decided not to use Nortons for escort duty/royal visits because of the smoking and I gather one had backfired while passing a dignitry!For high mileage / regular use, Rotella has proven to be quite adequate as Tony P has proven with his 468,000 mile Interpol.Malc

[Interpol2471]

Thanks all, well I pick up my Silkolene Friday at about 8-9 pound a litre from a local small shop so I will give it a try. :D

[kanonkopdrinker]

The ROC has plenty of Rotella DD+40 in stock at £2.50 per litre ... I remember Richard telling me years ago that in his opinion, there was no difference in the lubricating quality of either oil ... only in the price.

[Richard Negus]

I confirm that Mid-West did carry out a test of different oil brands, but not of differing oil types.The test at the time was on a single rotor water-cooled engine, type IAE50R, producing around 55bhp at 7,750rpm; the tests were part of a CAA approval process to certify an alternate oil to Comp 2 which, at the time, was the only permissible oil for certified MWE engines.Bardahl KGR, a synthetic two stroke oil blended in Italy, was tested against Comp 2 in back-to-back endurance tests of , I believe, 50hours scheduled running simulating actual power settings of the engine in flight. The engine was run on a mobile propeller rig out on the airfield at Staverton.The engine was stripped after each run, carbon deposits recorded and wear measured. Finally the engine was run for several hours on one oil, the tank drained and refilled with the alternate, run for more hours, drained again and filled with the first oil, run again and then stripped. No difference.Although the tank was drained as much as possible, the pipe from tank to oil pump was not drained as it was felt that the small cross-section of the pipe would not allow the oils to mix.At no time did MWE conduct observed tests with mineral oils such as Rotella.On a related subject, some MWE engine customers had end-plate scoring problems even when running on Comp 2 ; only the introduction of molybdenum coating of the entire wear face solved this problem. The narrow moly track developed for motorcycle engines by Tony Squire and myself in 1994 was a balance between effectiveness and cost. There were other, earlier, ideas to combat plate scoring ; David Garside thought that relieving the rotor sides in the pin seal area would alleviate the problem ; Hamish Munro of MWE believed that relieving the side faces everywhere but the corners would fix it. The result is that there are now rotors in use with no relief, relief at the tips, and rotors with relief along the sides. Apologies for the rambling - I'm still getting used to being 'retired'.R.