20W-50 is far too thick. Signs of a badly worn engine if required. 20W-50 was produced for Sir Alec Issigonis Engine/gearbox combos from Mini to 1100 to Landcrab (Austin 1800) & sheared hopelessly out of grade due to the gearbox chopping up the VI Improver. I have written about this at length ~ search This forum & read this (Preferably the whole thread).

http://jagstyperegister.com/forum_ne...iscosity#p3642

Jaguar never recommended anything higher than an SAE 40 & that only in tropical conditions.

If you want to delay the inevitable you can stick any old treacle in the thing but the engine requires rebuild. 20W-50 is the wrong recommendation for XK engines.

 

I use 10/30, synthetic oil and filter, the engine was done 20 years ago with very little millage since, modern machining and all that.
Has nice oil pressure on cold start up and even quite high once warmed up at idle _ I would not want it any higher.

I think too high an oil pressure can damage the bearings and crank _ Glyn, I think you would know about that _ something to do with foaming action under too high an oil pressure ???
I remember mine being right on the edge of the upper limit.

I'm not going to get into an argument over synthetic vs dino oil, not here, unless someone asks _ I have my reasons why I know use synthetic.

 

https://www.jaguarforums.com/forum/m...thread-232263/

 

"I use 10/30, synthetic oil and filter, the engine was done 20 years ago with very little millage since, modern machining and all that." An excellent choice with modern machining tolerances & parts.

Excessive oil pressure is unlikely to cause too many issues other than leaks. It could cause air entrainment in some circumstances. Air is not a good lubricant. But high oil pressure is seldom a negative.

10W-30 Synthetic is what my car will run on after run-in/break-in. I have cases of it sitting in my garage with a slight 229.5 additive level boost ~ the joys of working in the industry 16% instead of 12%. An absolutely ideal grade ~ 5W-30 or SAE 5W-40 are also OK.

BTW ~ what is dino oil in your speak? A reference formulation???

 

That's a "red-neck" term for non synesthetic oil.
Dino is short for Dinosaur.

So yes, a reference formulation, made form old Dinosaurs.

 

LOL ~ Sorry I was not familiar with that term. I was thinking has Jeff spelt dynamometer incorrectly etc.

 

Everything has its correct lubricant from dinosaurs to sun dials.

Doesn't the the higher viscosity synthetic oil, > *-30, have more ZDDP, for those who feel a need for it?

 

15W-40 is the grade affected by ZDDP levels ~ long story that I have covered somewhere. Plus there are many ways of formulating around lower ZDDP levels with superior additives. Just cost a little more. A storm in a teacup in many ways. If you can get around AMG's arduous HTHS (High Temperature High Shear) test you have cracked it. They have the highest power density & thermal efficiency on the market & run very aggressive cams. Remember who they power outside the Benz stable (e.g Pagani & Aston Martin rockets) and their own 2 litre A Class rocket. Then there is the 800> bhp 1600cc F1 engine at >51% thermal efficiency that has won them 8 constructors titles in a row. They have a big say in Brixworth.

 

Refresh page for edits. BTW ~ I Plasti-gauged every bearing in my engine.

 

I wasn't aware that new synthetics even had any ZDDP levels at all ?
I thought that went out with the dinosaurs with synthetics given the fact that they have far superior wear additives now.

Peter, your statement assumes that there is still ZDDP in todays oil _ generally speaking.
Given that, I still can find oils that clearly state that they have ZDDP additives in them _ for the old school crowd with their Corvettes and Camaros who still think that synthetic oil is bad for old cars.

I thought that ZDDP wasn't used in modern engine oils anymore because it would plug up the catalytic converters, and also the tiny oil offices in the cars valve train ?

EDIT:
Did a quick search and found this:
"ZDDP volatilizes, enters the exhaust stream and coats the converter's catalytic elements with the phosphate glass, preventing the exhaust from contacting the catalyst. The result is a shortened catalyst life"

 

Jeff, It also burns off the catalysts when they are hot enough, so they can cope with small amounts especially in an engine that allows negligible oil into the combustion chambers or one that spends a lot of time at high load. I think API SJ and on reduced ZDDP and may also specify lower viscosity. Certainly, ZDDP hasn't disappeared. Glyn can correct me on all this.

Personally, I'd not worry about ZDDP in our cars. A more reasonable fear of modern synthetics in old, unrestored (especially neglected or less cared for) engines is that the cleanliness packages might free up some trapped dirt that subsequently blocks an oil way. However, such an engine, if it exists, probably needs rebuilding anyway.

Jaguar and most old-time British engine designers were careful about lubrication requirements, generous with getting oil around the engine and didn't worry about the cost of drilling holes and adding oil tubes. In the 1970s and 80s, some manufacturers, notably Ford and GM, decided to save up on moving oil around. Their camshafts received a lot less oil. By coincidence (??), it was about this time that more exotic steels were adopted for camshafts and hydraulic lifters were becoming more popular. Their owners might have more to worry about.

 

Sorry for my response. I used 20/50 in my wife's GT6 for 14 yrs and 190,000 miles thru Illinois winters. All my Jags from 1957- 1986 got the same oil as recommeded by the service manuals. Noticed someone mentioned sensors, so I wasn't on the right forum. Thought it was the 1955- 1966 sedan forum. Sorry. Only been working on Jags and British cars since 1964. Had a 84 XJ6 fail emissions with 30W.

 

In fact, back in the day, that's what almost all of us used, most often Castrol or Duckhams 20/50. They were Jaguar recommended multi-grades for our cars and served us well.

 

Peter, that quote from the internet was just one quote, I also found a other places such as you tube that said just what you mentioned.
Not that I'm doubting you.

And about the dirty engine thing and synthetic oil dissolving enough dirt getting caught in the oil galleries _ I don't agree with that at all, I believe it to be a myth, or urban legend.
These detergents to clean things, are to keep things clean, they're not meant to clean things in an old engine filled with lead deposits and sludge, I don't believe any product does that, although there are many that claim that they do.
That's just my opinion though.

 

Jeff, agreed.

 

as i understand it, multiweight oils were developed so as to avoid contant oil changes that were necessitated by a change of season and their temperatures. IOW, a 10-50w oil was as effective as a 10W OR a 20W OR a 30W...OR a 50W oil. additionally, it made the purchase of oil, BITD, a sometimes quart per fillup necessity, less problematical.

 

ZDDP is still around because it's cheap. Jaguar never really recommended 20W-50. 40 was their highest recommendation. with 20 winter 30 summer & 40 tropical zones.

20w-50'S were very much a UK thing for Sir Alec Issigonis engine/gearbox combos. Most US engines ran on 20W.

With initial reduced ZDDP 15W-40's they were sacrificing engine life for emissions control gear. The oilcos soon got around that.

If a vehicle failed emissions on a SAE 30 it was worn or poorly machined & required rebuild. Going to thicker oil was just delaying the inevitable.

 

Then the engine was worn or just badly built on Jaguars ancient tooling. BTW there is no such thing as a 30W

This thick is good is nonsense & slows oil flow at cold start accelerating wear.

Old bad habits die hard with old mechanics. The Oil Industry has tried to train them with little success outside Asia where they listen & learn.

As a tribologist never ask your mechanic's opinion on lubrication. It is a subject they know FA about & are not trained in. Their skill set lies elsewhere.

 

A 5W-40 or 0W-40 is for global use all year round without change & provides complete protection without such change. From the Arctic to the Sahara.

 

I always use a multigrade starting with 0W for all my cars. It gets the oil up into the engine as fast as possible.

I have a friend with an old Lincoln that can sit for extended periods before being driven; with 10W-30 the valve train would make a huge clatter for about 30 seconds until the oil made it up to the top of the engine. When he switched to 0W-30 it makes a bit of noise right after starting, but it lasts for a much shorter period, as the OW oil flows so much better when cold.