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Synth. oils in old TRs... 6000 mile break-in?

Alan_Myers

Luke Skywalker
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Hi all,

I recently read a post here in which someone mentioned they planned to use synthetic oil in their TR shortly after a rebuild, but wisely not for the initial break-in period. I don't recall which post that was, but their intention to switch oils after 250-500 miles concerns me.

I know this is a hotly debated subject, but wanted to pass along some points Roger Williams makes about synthetic oil in our old cars, in his restoration books covering all the TRs. Keep in mind that in the course of writing his books William interviewed many of the TR specialist in England who have extensive experience with the entire line of Triumph motors.

Based on the information he gathered and his own engineering background, Williams recommends not using any synthetic until the motor has had 6000 to 9000 break-in miles. This would mean no synthetics until the the fourth or fifth oil change after the rebuild (1st change at 500, 2nd at 3000, 3rd at 6000, 4th at 9000).

The primary reason for this is the bedding in of piston rings, to prevent glazing of the bores due to the more slippery nature of synthetic oils.

Of course, different rings bed in at different rates and even the preparation of new liners effects the rate of break-in. For example, the rings provided with AE Hepolite pistons (OE) are generally known to be slow to bed in, but should give long service life if properly bedded. In fact, in the past racers have often tried to avoid the Hepolite rings. This is for the same reason they often have engines built to slightly loose bearing tolerances, rather than factory specifications. A race motor doesn't have much opportunity to break-in and are rebuilt very frequently compared to street cars.

On the other hand, slow break-in/long service life sounds ideal to me, for a car not destined to go directly to the track. Too bad AE Hepolite pistons, liners and rings are tough to find these days.

Other brands of rings may bed more quickly, but personally I'd rather err on the side of caution, allowing the motor a full opportunity to break-in before switching to synthetic oils.

The other main reason to think twice about many synthetic oils Williams mentionse is that many such oils are formulated with a much higher detergent content. This is particularly true of "long life" or "extended service" motor oils intended for 7500 miles or more between changes.

High levels of detergents may actually be detrimental to older engines, designed to run on non-synthetic oils. Over-cleaning of the engine can result in more blow-by around the rings and other negative effects.

I've personally had bad experiences with two cars (neither a TR), both with low to moderate mileage, that were switched to full synthetic motor oil. Both developed noisy hydraulic lifters and I suspect higher levels of detergents may have been the cause.

So, if you really feel you must use full synthetic motor oil in your baby, and wish to follow Williams' advice, wait for a new engine to have 6000 to 9000 miles on the clock and look for a low detergent variety of oil!

Finally, the gearbox seems to be an area where sythetic oils might best be avoided. A number of TR owners have reported their otherwise reliable gearboxes started popping out of 2nd gear after they switched to synthetic oil. Changing back to non-synthetic seemed to cure the problem.

Cheers!

Alan
 
FWIW, have used synthetic in the gearboxes for many years and experienced no problems. Perhaps in a worn gearbox it can bring out a problem which had not previously manifested itself?
 
Thanks for the post and the sum of all your research. I think it might have been my post that you're referring to for switching to synthetic on a rebuild.

I didn't look at the post, but I probably made a typo (or wasn't thinking) saying 250-500 miles on the switch. I wasn't planning on switching until about 1500 miles, but your points are well taken. There's a lot of conflicting evidence it seems on using synthetic oils, but nobody seems to have practical experience with a TR (or other old brit-car).

My personal experience in other cars (newer) is that the synthetic seems to keep the car running smoother and cleaner, as well as keep the compression up for a bit longer. One of the reasons I switched in other cars was the idea that synthetic has a better "coating" capability when your engine is off and sits overnight. Obviously I don't have a way to validate this other than what the "experts" say, but I feel better thinking that my engine is a bit more protected at startup in the morning because the oil clings better.

In my opinion, the best thing to do is to use a high quality oil filter, regardless of what type of oil. The junk that goes through your filter and gets stuck in your engine parts is really what can cause the damage.

I realize this topic will probably get a lot of emotional responses on both sides of the issue, but I like to listen to everyone's opinions on it.

Thanks!
 
I should think most people would shudder to see that high dollar oil dripping onto the driveway, when they could have saved a bundle on conventional oils!!!
Bear in mind most racers dont use synthetic due to cam problems that dont surface with regular oils.....
I like to have BRAND NEW clean oil 3 times as often for the same price...
MD(mad dog)
 
I put in Castrol Synthetic Blend -- which is a hybrid synthetic and conventional. My reasoning? It was on sale and 50 cents a quart cheaper than any of the conventional 20/50!
 
I used Mobil I in my TR3 for about 15 years. I used Castrol for the first 10,000 mi, however. Two years ago I pulled the head for a valve job and was amazed at the like-new condition of the bores. As impressed as I was with the Mobil I, I went back to Castrol after rebuilding the head because my 3 was leaking quite a bit and I thought perhaps it would leak less with conventional oil. It might be leaking a bit less, but the difference does not seem significant.
 
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