• Hi Guest!
    You can help ensure that British Car Forum (BCF) continues to provide a great place to engage in the British car hobby! If you find BCF a beneficial community, please consider supporting our efforts with a subscription.
    There are some perks with a member upgrade!
    **Upgrade Now**
    (PS: Subscribers don't see this gawd-aweful banner
Tips
Tips

Detergent/Non-detergent

Share this page

vette

vette

Darth Vader
Silver
Country flag
Offline
Well go ahead and load up your weapons, the bullseye is right on my head. :smile: I decide to start another post because I didn't want to hi-jack tomnanny's thread about an oil leak. But I had been following the discussion with great interest and finally I must ask this question. I have always found it intriging that in researching the topic of oils for our Transmissions and Overdrives, I always end up at the Shop Manual or the "Austin Healey 3000..Driver's Handbook". Neither of these contradict each other so I will stick with the 'Driver's Handbook' for simplicity. In the handbook, on page 63, in the list of recommended lubricants, it list at least (3) "Multigrade" oils for use in the Engine/trans/carbs. I have never heard of a "Multigrade Detergent Oil". So if the DHM company was recommending Multigrade oils, then they were by inferance at least allowing a non-detergent oil in their transmissions. The argument about GL4 & GL5 oils is not relevant to the discussion of detergent vice non-detergent because GL5 does not denote detergent. But I do understand the differences between GL4 & GL5 and that the GL5 is for the higher pressure applications such as rear end gears. Dave.
 
John at Quantum Mechanics states that he won't honor the warranty on an overdrive unit if it's been run with a detergent oil.

That my friends, is the full depth of my participation on the subject ;)

attachment.php




IMG_9391.jpg
 
Well:
The average motor oil today comes as a multigrade with a standard mix of detergents, additives, corrosion preventers and a number of other chemicals. All of these elements are expected to help engines work better and longer.

However I have read, some metallic parts in the early trannies are subject to damage from some detergents.
 
Boy did I screw that statement up. I was suppose to say " I never heard of a Multigrade Non-detergent Oil ". So as John said, he has never heard of a multigrade non-detergent ..... and as said, "if your using a multigrade oil, it has detergent." Then how's come the shop manual and the Driver's Handbook specifies at least (3) brands of multigrade oil. I've never seen the words " non-detergent" used in any shop manual or pubication from the factory.
Having beat this subject to death, and I do appologise for that, I could speculate that there is something in modern oils that may be affecting the yellow metals. And I can't argue with the people that say they have seen evidence to that effect. But the DHM company didn't seem to have any inferance about detergent or non-detergent oils.
Ok, I'm done, said my peace. Just had to get it off my chest. Dave.
 
Randy Forbes said:
John at Quantum Mechanics states that he won't honor the warranty on an overdrive unit if it's been run with a detergent oil.
Click to expand...

Why? Does he have hard evidence that detergent oil destroys ODs?

I know QM are acknowledged OD/gearbox experts, and Randy's a pro, but--being scientifically-inclined and a skeptic--when I hear a blanket statement like that I want to hear the logic, theory, statistics and, best of all, some proof. I've seen a lot of experts, not to mention some darn good mechanics, say something as fact but what it really is is conventional wisdom; e.g "that's what we've always done," "that's how I was taught to do it," etc. I believe the theory is the detergent keeps small particles dispersed instead of settling to the bottom as god intended, which causes them to plug small passages. I also know that air-cooled aircraft piston engines should be run on non-detergent oil for the first 50 hours of operation or so, because the ND oil causes high levels of wear that are required to properly bed the rings in very roughly-honed cylinder walls (people have been known to put Bon Ami in cylinders that didn't wear in properly in an attempt to grind the rings and walls). Also, over the years the terms 'detergent' and 'dispersant' have been muddied--I believe the former was added to help clean out lead and carbon deposits in older engines burning fuel that tended to run dirtier, and the dispersant is used to keep tiny bits of crud--mostly carbon--in suspension so the filter can trap it, but I may be mistaken. And between this forum and the email list I've heard lots of people with OD problems, usually electrically-caused, and the occasional worn accumulator or ball valve that quit working properly, but I don't recall anything attributed to crud in the oil.

I got my BJ8 at 64K miles, and AFAIK the OD had never been opened (it's possible). I've since put over 120K miles on it, most of the time running 20W-50 engine--yes, detergent--oil, and it's been flawless except for a faulty switch and relay. I now run MT-90. I bought a new master cylinder a few years ago, and on the box was a sticker that read 'Warranty void if used with silicone brake fluid.' I thought about it for about 3 seconds, installed the M/C and topped off and bled with fresh--you guessed it--silicone BF.
 
If the purpose of detergent in lube oil is to keep soot produced by the combustion process in suspension it would seem that detergents are not necessary in an overdrive. As to why detergent oil is harmful I have never heard an explanation beyond the one that since the detergents take up a certain portion of the oil's volume there is less lubrication going on per quart with detergent oil versus non-detergent. That sounds pretty lame.

Not having an overdrive in my Toyota-equipped car I am but a dispassionate observer here. But like Bob I too am an amateur skeptic and I do believe that with the advent of search engines much of what passes for fact is, in fact, conventional wisdom dressed up in a nice package.

However there is much to be said for empirical knowledge (read: observation and experience) and I generally do not go against the advice of those who have more than me of those two items without good reason.

To learn the basis for Esposito's reasoning go here: https://www.quantumechanics.com/qm-htm/topic1.htm

John does not say "why" but just "what" and if I had an OD in my car I would be using ND oil.
 
Well, that explanation makes sense. Based on that bench experiment, I would expect using 10W-30 might cause intermittent operation of the OD in the car; the 20W-50 I used to use--Castrol, usually--must have been thick enough to prevent that. I do believe--manual not handy--that 20W-50 is recommended in my Bentley reprint of the official shop manual. I would have liked to have seen the experiment conducted with a wider selection of oils and viscosities. Also, you would think QM would allow use of synthetic oil--since the results were 'OK' and if the owner could tolerate the extra leaking--since synthetic oil is generally acknowledged to be at least somewhat better than dino oil in most regards.

This statement: "We surmised that the detergents in the oil were causing the oil pump to cavitate, and develop air bubbles as it pumped." makes me wonder how detergent oil could ever be used successfully in any engine, as there are plenty opportunities for the oil to froth and cavitate (though not as many as in a gearbox/OD I will concede).
 
The Bentley manual does list 20/50 as well as 20/40 for use in the engine and the trans/OD. As Mike has said that thru the use of the "unquestionable" (my words) web, I have come across a post in the AACA Forum where they were talking about the fear of using a Detergent oil in an older engine that had been run on Non-detergent oil for many many years. It was said by one poster that there is no such thing as Non Detergent Oil. Only in that the later oils (detergents) have additives that keep the carbon molecules from linking up and setting and sticking to surfaces. That the term "Detergent" was really a marketing concept inferring that it keeps the engine cleaner. But an oil that is considered a detergent oil has no ability to break down existing deposites of crud. So to me that still leaves the question of , ' do newer oils with contempory additives threaten yellow metals in older gear boxes' ? We have testimony from relevant sources on both sides of the question. One is observations during disassembly and the other is experienced use with no determint. I guess again because of the equal bliss and curse of the World Wide Web, many of us may never know for sure. Dave.
 
https://www.mgtoronto.com/pdf/Tech/Overdrive_oil.pdf

That's I nice article about the merits or should I say the demerits of using 90wt oil. But it doesn't address the discussion of using a "detergent" oil verses a non-detergent oil. If anything the writer assumes that if he is to use a straight 30 weight oil it should be non-detergent. Again the earlier article as presented by Michael, written by Quantum Mechanics, makes the statement about evidence of deteriorated yellow metals by use of detergents. Yet what those detergents are, and are they present in most contempory oils is yet to be defined. Will we ever know, I guess our own experiences will define most of our positions. Dave.
 
Vette--

In his article Esposito only addresses the question of whether or not detergent oil is suitable for overdrives. He does not make any conclusions about which oil is correct for transmissions with brass synchros.

The corrosion to brass synchros and other yellow metals caused by GL5 oils is due to the higher sulphur content in "Extreme Pressure" hypoid oils, thus the recommendation to use GL 4 oils as is found in this article: https://www.widman.biz/uploads/Transaxle_oil.pdf

Of course if one has a synchromesh transmission with an overdrive that shares the same oil--such as do most Healey owners--then both concerns must be addressed and the right oil will be one that is good for both units: Ideally it should be non-detergent and non-corrosive.

I'm not suggesting that we ignore factory recommendations and I don't know whether "dedicated" manual transmission oils existed back in the day. In any case now one can buy an oil (such as Redline MT90 or MTL or other brands) which is specifically labelled for use in transmissions that does not have detergents in it. And since detergents are not only suspect for overdrives but unnecessary for transmissions why go elsewhere?
 
BTW I welcome all divergent views and would be happy to continue this discussion ad nauseum. I am getting close to 2000 posts and when I reach that plateau I think I get a free toaster from Basil, so please BRING IT ON!
 
Michael, I agree we can continue ad nauseum and I would like to very much help you to gain the object of your quest, that being the Free Toaster. So with that said, It seems that my understanding of the two articles and your remarks is that only the GL5, (extreme pressure) oils have the higher sulfer content which is what is causing the wear on the yellow metals. But I believe then that the general opinions about the use of High Detergent Motor Oils being deterimental to the yellow metals is still an outstanding issue in our discussion because I don't propose using GL5 oils in the trans/od But I do propose that there has been experience that the typical 30w, standard, single viscosity, detergent motor oils used in engines, not extreme pressure gears, have been used for some time in older transmissions with no determent.
BTW, I also welcome divergent views and find open exchange of ideas to obviously enhance our learnng. in truth I had for years never given this subject a second thought. And I have a few older transmissions in which I have used regular 30w, detergent motor oil such as havoline straight 30w, in them and have been running the transmissions for over 20 years, they seem fine. But having heard this business about the non-detergent oils I am truely curious, and concerned, maybe. So i am not talking about GL5 (extreme pressure) lubricants, I am talking about regular , straight, single viscosity, 30w motor oil. That is what is stated in the Shop Manual. As well as some multi-grades. Both would be considered detergent oils. Dave.
 
Vette--

Whatever... I'm heading out to buy some bagels.
 
John--

If you guys don't hurry up with posts to which I can respond I am going to have to start some topics of my own!
 
" If you guys don't hurry up with posts to which I can respond I am going to have to start some topics of my own! "

Oh No, No don't do that. I'm wulped now. :smile-new: Dave.
 
While at Rendezvous 2013, Steve Day, one of the Left Coast Healey experts had a discussion on oils, both engine and otherwise. His recommendation: use whatever your rebuilder says. That way, if there's a warranty problem, he can't claim it's the oil.

If that recommendation isn't applicable or you're out of warranty, he recommended a book Which Oil by Richard Michell. Richard's background is listed on Amazon:

Richard Michell is a 64 year old Chemical Engineer. He developed through necessity a knowledge of the mechanical aspects of cars while at university, driving an MG TD and helping a fellow student race an MG-B. He put this knowledge to good use some years later when he joined an Australian petroleum company and took responsibility for the formulation, manufacture, and sale of its full range of lubricants. In 1989 he joined a privately-owned company that specializes in the contract manufacture of lubricants. He still consults to that company. Richard has owned many cars in the years since that original TD. His current collection includes a Porsche 912, a Lancia Beta Spider, and an Austin 7 Sports. He uses his cars daily and does his own servicing and maintenance.
Click to expand...

One of the key takeaways from Which Oil is that you have to remember what oils were available and were like when the cars were new. In the 50's multi-weight oils were not commonly available. In the 60's they were, but under high shear conditions, the viscosity improvers (VI) which were used to achieve the multi-grade characteristics, tended to easily break down, so that a 10W/30 might break down to what would be 10 Wt or 20 Wt oil, not a good thing. Modern oils are better at not breaking down. So the recommendation of a 30 Wt in the 50's and 20W/50 in the 60's, which might break down to the equivalent of a 30 Wt. By having the same oil recommendation for the engine and transmission (Bentley Manual) means you only have to carry one oil container. If you drove a Mini, the transmission was in the engine crankcase, so you had no choice.

BTW, on the subject of detergent/non-detergent, detergents make no difference in transmissions. They are needed in engines but detergents do no good and no harm in transmissions, and cost more than ND oils (in the 50's).
 
Back
Top