"syner G" in a zetec

[Casbar]

Fast Westie - I have a xflow which has just been re-built using forged pistons etc. Before the re-build I used to use Mineral oil, I now use Mobil 1.

 

Guess what, oil pressure exactly the same, and if anything it uses less oil than before. Infact it only uses about half a pint every 500-600 miles.

 

I changed to Mobil 1 on advice from rep engine builders. My mate also has a xflow and he has always used Mobil 1.

[James Arnold]

Phil you said

there is no such thing as a thick or thin oil, it is fast or slow.

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The study of fluids in shear and under pressure etc is a topic for weighty text books (I used to have one), and my memory is less than clear but this statement doesn't make sense to me.

I know we are talking loosley, but the whole point of oil is that it is a lubricant and forms a fluid layer between surfaces. The viscosity of the fluid is crucial - in this case surely viscosity = 'thickness'. Whilst the 0/40 type number may be determined by the speed an oil runs through a hole, this is a measure of its viscosity (thickness). Whilst in absolute terms thick and thin oils are hard to define, there are definately thicker and thinner oils.

 

The 'fast or slow' aspect does indeed have effects on cold starts etc, but is a side effect.

J

 

 

 

Edited by - James Arnold on 22 Feb 2002 15:29:50

[Peter Carmichael]

Generally pick an oil based on the second number and suitable for your engine.

 

K's generally like a 40.

 

Zetecs like a 30

 

VXs seem to like a 40 but can be fussy. Some owners swear by 50s.

 

XFlows seem to like a 40, but by reputation a 50 can sometimes be a good thing.

 

The first number should be a low number. 0,5 or 10. Synthetics manage their viscosity very well over a wide temperature range. Mineral multigrades needed to have lots of viscosity modifiers to handle a wide temperature range, meaning that there was proportionally less load bearing lubricant. A 15/40 mineral oil was a good grade of mineral oil because it was almost all lubricant rather than additives package. With synthetics this doesn't matter half so much, so 0W40 is bloody marvellous stuff.

 

Slick50 is engine destroying rubbish. There is no possibility of the PTFE actually sticking to the engine surfaces. All the manufacturers claims are bogus.

 

The noise your tappets make is down to the hydraulic plunger getting stuck and giving the wrong follower clearance. This can happen in different ways with different engine designs. When the clearance is too large, the tappet gets a hammer blow from the cam rather than a smooth uptake, so it is important to get them working again as soon as possible.

 

Valve stem seals tend to get worn in older engines. However thick the oil eventually the valve stem seals are going to give up. It is very unlikely that the major clearances of main and big end bearings will grow significantly over time, so their demands for an oil of a given thickness remain much the same.

[Phil]

thanks to everyone pionting out the slick 50 thang, interesting reading and I shall look futher into this and hold fire with the treatment at present.

 

Fast Westie, what is an old engine or do you mean old design. It doese not matter how old the design if it is built with modern machining, clearences and better materials to perform better, be stronger and last longer demanding modern oil to support this, or do you think I should use 20w/50 as this is was the oil available at the time of design?

 

I would like to explain that I was trying to get people away from the terminology of thick and thin as this leads to ignorance for example, my engine is old so I will try a thicker oil, thus taking away cold start up protection and the required additives to keep it clean which is WRONG.

when a 15w grade oil is heated does it not travel through the same viscosity hole as quickly as a unheated 10w, yes it does so by adding heat are you thinning the oil, the lower number the oil starts with means it flows quicker because it is pure and clean and not packed out with impurities.When making a semi or fully synth oil they are using only the parts needed to do the job so you get maximum lubrication.

 

 

 

 

 

[Phil]

imagine a football match and all the fans standing outside with a suitcase in each hand and an = number of fans waiting to get out holding the same, the suitcases are the impurities,as the gates open and all the fans try to get in and out catching each others cases and everyone heading in different directions,now take all the fans going in and tie them all together in a line and remove there luggage and do the the same to the ones coming out, now open the gates, they all pas smoothly and very fast and without damage to each other. The chain of oil and its resistance to braking down is called shear quality and the better the oil the better the shear quality, longer stronger chains of oil moving freely and doing a better job.

 

 

[Mark Piper]

Peter C - thanks for the posting - you explain what the problem is re hydraulic plunger etc - what's the cure? will flushing cure it? or is there any need to replace the tappets?

 

 

[Tight fart]

I have run out of oil in a engine treated with slick50 with no harm done.

Speak as you find I rate it very highly

[westy]

I remember reading that slipperyness (thats might not be the technical term) was measured against wet ice on wet ice, and that ptfe was the closest you could get!

 

[Peter Carmichael]

I have run out of oil in a engine treated with slick50 with no harm done.

Speak as you find I rate it very highly

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How many non-treated engines have you run out of oil with?

[Tight fart]

One other, it seezed.