Everything you wanted to know about Oil (but didn't know you did)

[oldtuckunder]

In my quest to find out what's happening to fuel mixtures in a CD carb I have found my self exploring more about oil behaviour than I would have believed, but in my travels I have found a wonderful resource.

 

http://www.bobistheoilguy.com/motor-oil-101/

 

Very well written

 

So if you want to know why water is a better lubricant than oil, why there is NO oil manufactured that is thin enough to provide adequate protection at start up, why its the thickning of oil thats the major problem not the thinning as it gets hotter, and why if you think 20-50 oil is good for your engine you are in for a serious surprise!

[Steves_TR6]

I started to read that, but will need wine to finish it!

[Eddie Cairns]

oldtuckunder.

 

A good site and forum.

 

Have you ordered your Blackstones used oil analysis sample kit yet.

[oldtuckunder]

I started to read that, but will need wine to finish it!

 

Great minds, guess what I did yesterday evening!

[oldtuckunder]

 

Have you ordered your Blackstones used oil analysis sample kit yet.

 

No but I have a lot of old "new" cans that will now go in the ferguson tractor

 

Alan

[barkerwilliams]

An excellent read, and progresses logically to conclusion. So the Halfords Classic oil is out.

 

Alan

[mike3739]

Why is Halfords Oil out?

[monty]

In my quest to find out what's happening to fuel mixtures in a CD carb I have found my self exploring more about oil behaviour than I would have believed, but in my travels I have found a wonderful resource.

 

http://www.bobistheoilguy.com/motor-oil-101/

 

Very well written

 

So if you want to know why water is a better lubricant than oil, why there is NO oil manufactured that is thin enough to provide adequate protection at start up, why its the thickning of oil thats the major problem not the thinning as it gets hotter, and why if you think 20-50 oil is good for your engine you are in for a serious surprise!

 

What a worry all this is! Thought I was doing the right thing by using Millers Classic 20/50 mineral in my cars because of the old technology of our engines, toyed with 20/50 semi synthetic or even synthetic & now more doubt! Always had more leakage whenever I have used synthetic in a previously owned MGC so went for mineral again. Never noticed any change in fuel usage or any difference in starting it whatever oil I used so am now more confused & unsure again!

Have not read all the article yet but do wonder how much of it is really applicable to newer engines rather than say TR or MG examples.

Cheers.

[TR5tar]

An interesting read, especially with a class of single malt to help with clarity. I'd be interested to hear Peter's views on the article, as he has contributed to many previous discussions on oil.

 

For those that don't know it, I found "Which Oil" by Richard Michell a great source of information relating to oil and classics.

 

I currently also use Millers Classic, but reading this article and the Q&A section in the Michell book I do start to wonder about using a synthetic oil.

 

Darren

[littlejim]

Would have liked Dr Haas to include reference to some research in the article, comes over more as an opinion piece.

Makes some good points, but I suspect that when I start up in the morning 'stiction' has left a bit of oil behind in the bearings. From what he says this will be thick and harder to squish out to get metal to metal contact. good.

Have a different view of additives. Thought molydi was a bipolar molecule and attached itself to the metal parts like that brown stuff to the Witney blanket.

I remember a report of the first additive, colloidal graphite, keeping a Redex trial car going for 50 miles after holing the sump and like the fact that my Prado isn't using oil at circa 500,000Kms after using Nulon treatments. Both these are anecdotal rather than research, but I'm happy with them as much as he is happy with his opinions.

Edited April 24, 2015 by littlejim

[GT6M]

Go and bung some thin oil in yer ebgines then,

BUTT, be prepared to see oil consumtion go way up.

 

And also hear the bottom end banging / rumbling away, cos its already got bigger clearances in bearings

at 30,000 thou miles, than any modern ever will have at 300.000 thou mile

And the oil pressure come way down, even at higher revs

 

I got some Castrol RS 10 / 60 at local factors aboot 6 years ago,

worst thing ever, used 4 litres in 700 mile round trip,

oil pressure even at cold was only showing 50 PSI

and doon to 30-35 at temp, no matter hoo high it revved.

 

And to top it off, not long after, I lost 4 lobes on the cam. and followers shot too. most had signs of wear.

Never had to keep adjusting the rockers befoer, but after that RS went in,

had to keep tek,n slack up in some adjusters, then when cam was took oot, the lobes had worn off.

 

After market cam, but it were OK befoer that RS,

just doo a search about modern oils and flat tappets, not v good reading.

 

Just me tuppence worth on actuall findings.

 

M

[DaveN]

Must admit I use halfords classic, but after noticing how thick it was I've been tempted with a 10/40 semi synthetic and a shot of Camshield. The only downside is the cost, halfords don't sell Camshield. This is the solution a mate uses in his ford Kent engined Lettuce7 even on track days.

[RogerH]

Fascinating read but!!

 

As mentioned above even a decent newly rebuilt 4 or 6 pot TR will have clearances bigger than any modern.

The oil galleries are like tunnels compared to modern engines and so retain a fair quantity of oil.

Indeed the oil gauge creeps up on start up but residual oil in the bearings will do a reasonable job at keeping the metal separated.

 

My 4A has done 150K on Halfords classic and I can't find a reason to dismantle it yet (although I keep looking).

The Ford engine'd Lotus is modern technology and requires modern oil.

 

Use what you know is best

 

As a thought - Castrol Magnatec sticks to the metal parts - how do you drain it out of the sump!!!

 

Roger

[RobH]

+1 Roger.

The evidence is that our engines have managed to survive very well for many decades of using various mineral-based multigrades. If it were otherwise, this forum would be swamped by talk about premature engine failures from using the stuff. Perhaps one should view any information/opinion found on the internet with a due degree of scepticism, if it contradicts experience?

I agree with Darren that 'Which Oil' is a good and informative book for anyone wanting to understand motor oils and is written by someone who actually runs old cars.

 

Rob

[TRseks]

The article was interesting.

 

But not sure about the theories about the problem with oil being to thick at low temperatures is really a problem, a thick mineral oil will in my opinion stick better to the parts than a thin synthetic oil when the engine is left?? Or am I wrong? Many old classics are used maybe a few times a month or hardly that. And as tolerances on a cold engine is bigger than on a warm engine thick oil that also stick better to the surface surely can't be that bad?

 

 

Thin oil in old engines does not sound right. Once I had a Kawasaki H2 two stroke 500cc, it had problems with slipping clutch. Even with new clutch plates and new clutch springs it would slip the clutch, someone said try atf oil in the gearbox (clutch was oil bath together with gearbox). I tried this but only running the engine for 20 seconds convinced me that it was a huge mistake as the engine sounded like **** with all sorts of noises.... Solution was to change oil back to thick gear oil and fit some washers to tighten up clutch springs.

 

I will continue to believe that a half worn old engine with much looser tolerances than modern engines will be better of with a thicker oil, that's why I bought mineral Penrite 20-60 last time, it has high zink and a tacky additive that makes sure it's a good oil for use in engines that is not used every day.

Edited April 24, 2015 by TRseks

[Peter Cobbold]

 

 

For those that don't know it, I found "Which Oil" by Richard Michell a great source of information relating to oil and classics.

 

I currently also use Millers Classic, but reading this article and the Q&A section in the Michell book I do start to wonder about using a synthetic oil.

 

Darren

Michell's book is specifically focused on 'our' engines.

 

As I never start the TR at minus 20C the BITOG article is not really relevant, and it doesn't mention old engines with bigger clearances, flat tappets etc. And the number of cold starts per year is tiny comapred with dialy drivers. It reads to me as being written for moderns.

 

Modern synthetics wont have any much ZDDP as it poisons cat converters. So that would have to be added to the correct level, not too much not too little.

And even if that is done the higher level of detergents in modern oils may strip off the zddp-cushion that protects the flat tappets and other rubbing surfaces ( rings, bores, rocker/valve/pushrod ).

 

So I shall use a classic oil with known ZDDP and the correct balance of additives - ie the manufacturer's formulation- to ensure it works.

What I have been doing wrong is running an oil cooler without thermostat. Oil temperature below 80C prevents the ZDDP from working. So I am going to ditch the oil cooler completely.

 

I recommend reading the chapter on lubrication in A Graham Bells book:

http://www.amazon.co.uk/Four-stroke-Performance-Tuning-Graham-Bell/dp/0857331256/ref=sr_1_1?ie=UTF8&qid=1429866904&sr=8-1&keywords=a+graham+bell+four+stroke

Pages 506-514 covers ZDDP.

 

Peter

 

And I focus on ZDDP rather than viscosity because the bits that have worn over 280k miles on my, mostly lightly driven, engine have been cam and bores. The journals are still original and within spec.

Edited April 24, 2015 by Peter Cobbold

[littlejim]

Dr Haas's degree is in medicine, but he has obviously played round with oils for his ferraris and other vehicles, and formed a few opinions on what he likes for his cars.

Can't argue with that, but I find his theories like idling his cars at low oil pressure to warm them up etc. at variance with current recommendations and what I prefer to do.

Dirty Harry covered the opinion situation nicely, applies to cars too.

[TR5tar]

Michell's book is specifically focused on 'our' engines.

 

As I never start the TR at minus 20C the BITOG article is not really relevant, and it doesn't mention old engines with bigger clearances, flat tappets etc. And the number of cold starts per year is tiny comapred with dialy drivers. It reads to me as being written for moderns.

 

Modern synthetics wont have any much ZDDP as it poisons cat converters. So that would have to be added to the correct level, not too much not too little.

And even if that is done the higher level of detergents in modern oils may strip off the zddp-cushion that protects the flat tappets and other rubbing surfaces ( rings, bores, rocker/valve/pushrod ).

 

 

 

 

Hi Peter,

 

I did get the impression that the article was more relevant for modern engines, so I didn't take much note of the author's preference for synthetic oil.

 

However, I've been meaning to raise this question for some time: what's your take on what Michell says on pages 119-120? He seems to be saying that modern synthetic oils from a reputable marker are fine to use in classics, especially in one that is high-performance and used frequently. Only downside, he says, is that synthetic is more costly compared to mineral. He doesn't in this part of the book make reference to ZDDP.

 

Darren

[oldtuckunder]

 

 

And also hear the bottom end banging / rumbling away, cos its already got bigger clearances in bearings

at 30,000 thou miles, than any modern ever will have at 300.000 thou mile

And the oil pressure come way down, even at higher revs

 

I got some Castrol RS 10 / 60 at local factors aboot 6 years ago,

worst thing ever, used 4 litres in 700 mile round trip,

oil pressure even at cold was only showing 50 PSI

and doon to 30-35 at temp, no matter hoo high it revved.

 

I think the point was that its the flow thats important not just the pressure, and that there is no one right oil, but that one should select an oil that gives the right flow according to the condition of the engine, and that a good measure (when the oil was up to temperature) was 10psi per 1000 RPM i.e when upto temperature at 5K RPM you should be seeing 50+ PSI.

 

So the fact that you were only getting 30-35 at working temperature at high revs says that you were using the wrong oil for the condition of the bearings.

 

Alan

[oldtuckunder]

 

As mentioned above even a decent newly rebuilt 4 or 6 pot TR will have clearances bigger than any modern.

 

Not wishing to argue, but the machine shop that just rebuilt my 6 pot say categorically that the tollerances and finish they use on all competition engines old or modern are identical, and that the journal clearances specified for my competition engine were virtually identical to any modern competition engine.

 

So what clearances that affect oil flow are we talking about? Large oil galleries are a red hearing 50 PSI in a 10mm diameter gallery is the same as 50 PSI in a 5mm gallery its just that a 10mm can flow more.

[RogerH]

No argument at all.

 

The article is a fascinating read and if anything will make the average owner perhaps think more about the life blood that flows through the engine.

 

Perhaps I was underestimating the quality/tolerances of what is being done now but our standard engine is a bit loose compared to modern technology.

 

As for flow - you need the pressure to get the flow into the tight area;s. The flow is important in removing excess heat from the metal and the oil itself.

 

The article has something for everybody - worth reading.

 

Roger

[Peter Cobbold]

 

 

50 PSI in a 10mm diameter gallery is the same as 50 PSI in a 5mm gallery its just that a 10mm can flow more.

Well, there's caveats on that.....

 

If the pressure drop is 50psi along a pipe then laminar flow is proportional to the fourth power of the diameter. So the ratio betweeen the 10 and 5mm bores is 10^4 to 5^4 or 160. So the bigger bore flows 160 times as much as the smaller for the same psi drop.

 

If the flow is turbulent the ratio is less but likely to be still large. But trickier to estimate ( Moody chart)

 

But its not really gallery flow that matters. The critical dimensions controlling gallery psi , when prv is shut !- are the journal/shell gaps. But we can expect very roughly that a gap that is twice as big and of similar length and area will flow oil far faster than twice as fast.

And then we have to worry about what happens to flow sharing between journals when one shell starts to wear....and starves the others of flow.

 

Peter

[RogerH]

Hi Pete,

oddly enough that is not on the back of the Halfords Classic oil can

 

Roger

[Peter Cobbold]

 

Hi Peter,

 

I did get the impression that the article was more relevant for modern engines, so I didn't take much note of the author's preference for synthetic oil.

 

However, I've been meaning to raise this question for some time: what's your take on what Michell says on pages 119-120? He seems to be saying that modern synthetic oils from a reputable marker are fine to use in classics, especially in one that is high-performance and used frequently. Only downside, he says, is that synthetic is more costly compared to mineral. He doesn't in this part of the book make reference to ZDDP.

 

Darren

Darren,

I agree he equivocates on ZDDP, Bell is more forthright.

To me, the worry with Michell is he doesn't specify what modern oils are compatible with ZDDP-coated surfaces. I have been using ZDDP since the TR was built, and to swap to a presumably completely different antiscuff chemistry worries me. The old layer of ZDDP will be replaced with whatever the modern uses ( boron maybe). Does that happen seemlessly without wear? Maybe I'd reconsider if the crank had been reground, the cylinders rebored and cam and rockers were new. So I see potential downsides and no real upsides to Michell's enthusiasm for modern oils. Its a pity he doesnt describe the modern chemistries and how they interact with the old.

Peter

[GT6M]

So the fact that you were only getting 30-35 at working temperature at high revs says that you were using the wrong oil for the condition of the bearings.

 

 

Odd on a minute, thats a daft statement, a 10-60 is supposed to be thicker than a 50W oil at higher temp,

So the oil did no act as it were supposed to doo.

 

Thats what I was inferring too.

In fact, if I bung a 5/50 in the MX, it gives moer pressure than the RS 10-60 did.

but by all the blurb, the 60W should give moer.

 

M