Which oil for smoothest gearbox?

[Andre]

It doesn't get better sitting around. If you chose to wait with the change till after winter, then store the oil in unopened container in a place that does not experience much change in temperatures.

I would change the oil now because the crud in the old oil is certainly not a benefit for the engine. Then change oil again when driving season starts. A lubrication specialist for a German car maker stated that oil (and its additives) is only good for 6 months. The 14's service manual prescribes a change every 6000 km or 6 months.

[Speedy1959]

Thanks Andre,
I agree with what you say about oil..
I am "Old School" and always change oil (Car and bike) regularly.
I have had 7 Mercedes cars.. Including the rare CLK63 AMG !! ( Only 25 in the UK).  What an engine that was !!!

[Andre]

My buddy got rid of his CLK. Just got him into trouble to often when barely touching that gas pedal 

Them German car makers are extremely fussy about engine oil. Use an oil that is not on their officially approved list for a specific engine and you lose the warranty.

[Hooli]

From everything I've read it's better to change the oil before parking the bike up.

From what I've seen & understood the impurities in old oil can fall out of suspension and collect at the bottom, which is fine in the sump etc but not so good in the film of oil in your bearings.

It doesn't concern me enough to do an oil change early before parking it up though.

[DTTW]

From everything I've read it's better to change the oil before parking the bike up.

From what I've seen & understood the impurities in old oil can fall out of suspension and collect at the bottom, which is fine in the sump etc but not so good in the film of oil in your bearings.

It doesn't concern me enough to do an oil change early before parking it up though.

I had to change the sump seal because it was leaking. There was a thick layer of crude lying on the bottom of the sump. Not sure whether that crude gets to move when engine gets warm but if it does I am sure it is no good. Therefore cleaned, of course, the whole sump. By that time my bike had around 26 tkm on the clock.

[Starion VR4]

Always use Castrol RxSuper Diesel oil, 15w-40 API. Been usung it since 20,000km's have 100,000kms. High detergent contraction & Turbo rated. Give it a try, you won't go back. 20L = $80-100

[Notty]

Just bought some Castrol from Halfords 20% off - wait and see how it is - oil change due now but should I leave it until spring ? won't be riding much more now winter is here 

Oil changed to Castrol Power semi synthetic and seems quieter but may be just due to fresh oil ( 2.5k since last change ) its started raining so will have to wait for a road test -  and no mess using the Fumoto oil drain valve I got from Dave 

[Andre]

Always use Castrol RxSuper Diesel oil, 15w-40 API. Been usung it since 20,000km's have 100,000kms. High detergent contraction & Turbo rated. Give it a try, you won't go back. 20L = $80-100

Have heard from several people who use diesel oil without problems. The manual states:

Use a premium quality 4-stroke motor oil to ensure longer ser-
vice life of your motorcycle. Use only oils which are rated SF or
SG under the API service classification.
The recommended viscosity is SAE 10W-40.

SAE 15W-40 (50) is acceptable IF no other can be had. 15W may not be that great for those driving through European winter
API SF (minimum).
No mention of JASO MA, MA2 (higher friction properties - good against clutch slipping, not so good for wear protection)

There is nothing in there saying NO diesel oil.

This is from the Castrol RxSuper Diesel oil 15W-40 datasheet:

Petrol Engines – using all types of fuel (unleaded, LRP, LPG & CNG).

Note: As with all API CI-4 and CI-4 Plus qualified engine oils, the phosphorous content does not
comply with Australian Motor Industry agreed limits for catalytic converter equipped petrol engines.
The higher phosphorous content may reduce efficiency and/or effective life of catalytic converters.

For those who have a 14 with cat (and care) the later is important.

More from the Castrol RxSuper Diesel oil 15W-40 datasheet:

SAE Viscosity Grade - 15W-40
KV @40 °C  cSt 125
KV @100 °C  cSt 15.9
CCS @-20 °C  6700 mPas
Viscosity Index 135
Pour Point  -33 °C
Flash Point (COC) 210 °C
Total Base Number  mg/KOH/g 10.9

From data sheet of the 100% synthetic oil I use LiquiMoly Motorbike 4T Synth 10W-50 Street Race

SAE class (engine oils) 10W-50, API SN, JASO MA2
Viscosity at 40 °C 123 mm²/s
Viscosity at 100 °C 18,5 mm²/s
Viscosity index 169
Viscosity at -25°C (CCS) <= 7000 mPas
Pour point -39 °C
Evaporation loss (Noack) 5,0 %
Flash point 254 °C
Total base number 6,3 mg KOH/g

When I compare the 2 oils I see the latter to be clearly ahead when it comes to dealing with high temperatures. Mind you that the temperatures in the 14's engine combustion areas see very high temps (not nearly as low as displayed on a thermo you might have sitting in the clutch area or indicated by the hardly ever active oil cooler fan).

The higher detergent content of the diesel oil is a nice touch, but that is sorely needed in a diesel that produces tons of soot.

AMSOIL, a leading US lubricant manufacturer shares their view about the need for motorcycle specific oils here https://www.amsoil.com/newsstand/motorcycles/articles/use-motorcycle-oil-in-your-bike/

[KiwiCol]

You go into a lot of detail on those oils Andre, lots of research & understanding - well done.   I don't think any 14's have a cat though. 

I'm of the opinion the 14 engine isn't a particularly 'high strung / stressed' engine, it seems quite happy with a multitude of different oils and grades. Yes there is a specified grade recommended & most seem to stick to it or something close, but as long as it's getting frequent changes they seem to keep going without too much fuss.

Can anyone actually recall a 14 engine suffering undue / premature engine wear or failure caused by incorrect oil? (I'm not talking about stuffing the clutch plates because of using friction modified oils here)  Be interested to hear from people on that.

[Andre]

Hmmm... than I might be the only one with a cat in the 14. It starts purring as soon as I hit the starter button.

I research stuff because I like doing so  ... and have nothing else to do 

What kind of oil you put into the 14 doesn't really matter that much. That is the opinion of my friendly Suzuki dealership guy who has been at the dealership for the last 15 years at least. However, he talked about engines of 50000 km!

Haven't heard of any engine damage due to the oil chosen either.

However, as long as I don't know anyone who has a 14 with 450,000 km on it, using a car oil (petrol or diesel) without engine failure running the bike semi-hard, I stick to the data sheets and what else I gathered from my research. I spend much more on coffee than on premium oil and premium fuel. 

[Hooli]

Can't help you with 450,000km, but mine is around 180,000km on Halfords own make 10w40 motorbike oil. Runs sweet & doesn't use a drop. Changed every 4,000miles (about 6,500km).

[T 24]

@ Andre
Nice research work, really.
I have used several 15 w 40 diesel oils in my bikes many years and over 250 000 km (total) with no problems.
Two years ago I had some idle smoking problems with my turbo 14 and I started to test different motorcycle oils. OK, the problem was not in oils, it was in my breathing system and it is solved now.
Some things I noticed in my "tests": Some motorcycle oils are not washing engine enough, they just leave the soot in the engine, and look "as new oils" when you drain them ( Motul 5100 was the worst oil I have ever used ).
I have seen pictures in this forum from opened engine cases and writings "how clean it is, I have used XXXXX motorcycle oil XX years".
In fact they seem VERY dirty engines to me, people just havent seen clean engines.
Now, at the moment, I am using Teboil 15 w 50 Super bike, full synthetic motorcycle oil ( API SH/SJ/SG, JASO MA, API GL1), but I cant see any differenses to Teboil 15 w 40 SHPD turbo diesel oil or Mobil delvac MX 15 w 40 oil.
And the differense how smooth gearbox is working, comes mostly from clutch.

[Andre]

The crux when looking at oils is that many manufacturers are very stingy about supplying data sheets.

Even if you have data sheets, "nice values" are not that meaningful by themselves. Important is how they were achieved. Did they use a basis oil that inherently achieves a substantial part of these values or have they dumped in lots of additives to achieve this. Many of the additives deteriorate rather quickly and you end up with the properties of a "cheap" oil whose properties may not be the best but much more stable in the long-run.

Having said that, I will not use a "cheap" oil but only those which exclusively use group IV basis oil with relative small amounts of additives. They have inherent top properties which are very stable.

Unfortunately we have almost exclusively anecdotal and subjective reports on how a specific oil performs.

What I do gather is that the 14's clutch is quite indifferent of the oil it gets.

And I agree with T 24 that gearbox smoothness is strongly affected by the clutch performance.  As I am not happy with my gearbox working, I will first get a new clutch slave cylinder and (left-hand) push rod. Someone reported that his old push rod was shorter than a new one (didn't provide the length of eiter one though). If still not satisfied, I will look at changing clutch springs (individual springs could be weaker than the others), clutch plates, right-side push rod, and SPRING 09444-20001 (changing this spring was reported to make shifting smoother when weakened, as well broken in some cases with and without resulting engine damage).

[Notty]

Just bought some Castrol from Halfords 20% off - wait and see how it is - oil change due now but should I leave it until spring ? won't be riding much more now winter is here 

Oil changed to Castrol Power semi synthetic and seems quieter but may be just due to fresh oil ( 2.5k since last change ) its started raining so will have to wait for a road test -  and no mess using the Fumoto oil drain valve I got from Dave 

Yippee the sun was shining so had a 100 mile run - seems smoother gear change and tick over - is this because its castrol or fresh oil ? good thing is the oil is red and sooo easy to check the level 

[Trav Man]

I run the Penrite MC4ST full synthetic with PAO-ESTER 10W-40 in both the GSX and the old DR and they both love it, Also most of my mates now run it in their dirt bikes as well and from all reports it's to quote as being "good shit"  from them all 

Heres the link for you Andre if your interested
http://www.penriteoil.com.au/products/categories/motorcycle-go-kart/4-stroke-engine-oils/mc4-st-10w-40-pao-ester
And here's the Date Sheet
http://www.penriteoil.com.au/assets/msds/MC4-ST%20Full%20Synthetic%20Four%20Stroke%20Motorcycle%20Oil%2010W-40%20Rev%200.3%200816.pdf