[RocketRon]

I've used only petroleum based oil for 2 1/2 yrs on my LT only because I was told several yrs ago that there was a possibility that synthetics were the cause of seals going bad prematurely.

Has anyone ever seen any hard facts or heard someone in the industry back that up?

I'm not trying to start anything...I'm a believer in synthetics but so far running dino sure hasn't hurt anything.

Thoughts? Facts? Hearsay?

Ron

 

[copperstatetour]

:corn:

This is going to be fun.

 

[RockMonkey]

Well, I can tell you what I have experienced first hand, both on the LT and on a Yamaha FJR1300.
Both machines experienced no problem whatsoever running Synthetic in the engine. Both machines have a problem running synthetic in the transmission/final drive.

When I first bought the FJR used, the original owner had warned me that he found synthetic weeped past the seal on the final drive. I stuck to Dino oil and had no problems, but the service shop I take it to had a new guy there that missed the note that said dino only in the final drive. I got the bike home and could see it starting to slowly weap past the seal. Took it back, cleaned it up real good, changed back to dino oil, no more problem.
The Output shaft seal on the LT needed to be replaced. As per BMW's instructions, they put the recommended synthetic in the transmission. Three days later the clutch was contaminated again. Tore the bike apart, inspected the seal, flushed the system, changed the clutch, put dino oil back in, and 7000 km's later I've had no problem.

I'm not endorsing one kind of oil over the other, only stating my personal observations.

 

[CharlieVT]

I've used only petroleum based oil for 2 1/2 yrs on my LT only because I was told several yrs ago that there was a possibility that synthetics were the cause of seals going bad prematurely. .......

Popeye likes Olive Oil, and she's the real thing. Nothing synthetic there.

On a slightly more serious note, modern synthetic oils will not harm modern seals. Wow, can you imagine the problems it it did?!?

I suspect this kind of urban legend got its start from the following observation: Some folks have reported that when switching old bikes from petroleum based oil to synthetic, that bikes that didn't have leaking seals would start to leak. This was not because the synthetic oil was damaging the seals, but rather because the seals being old and worn were more likely to let the smaller, more uniform molecule size of the synthetic oil past the seals.

 

[TWheels]

I use synthetic in the transmission and in the final drive. Both on the LT and the now the RT. Never had a problem! But ..... I use dino oil in the crankcase. Why ??? I change oil and filter regularly and don't understand why I should spend more money for synthetic oil..... Perhaps there are theoretical advantages to synthetic but I do not know if there are any practical advantages.

 

[RocketRon]

Rock...That's exactly what I'm afraid of with my older LT.

Charlie...what you're saying about the molecular size of synthetics makes sense. My LT, being an '02, will probably be better sticking with the dino. I still have to wipe off a little residue from the back wheel from time to time....I think I know what's in my future but I'm not going to jump to conclusions and tear it apart right now.

 

[RockMonkey]

CharlieVT: You are right about the synthetic not damaging the seals. The problems I encountered were not from damaged seals, the synthetic didn't harm them that all. Perhaps because of the molecular reason that has been raised a few times, the synth just seemed to weap past the seal, but the seal itself was just fine, no harm done whatsoever.

 

[katnapinn]

On a slightly more serious note, modern synthetic oils will not harm modern seals. Wow, can you imagine the problems it it did?!?

.

I used Synthetic oil in my LT for over 65K miles with no leaks ever. I switched from Dyno to Synthetic at 18K as my dealer recommended. They said not to switch till 18k so the rings would set in properly.

 

[deanwoolsey]

I have to disagree with Curtis. Synthetics do cause the rubber seals to be more pliable and as he eluded to, in older engines this can be an issue. Here's a case in point. My next door neighbor took his late 80s Ford pickup into Wally World and they sold him on a synthetic oil change. A week later his driveway looked like he owned a whole fleet of AMF Harleys. He had oil standing in a puddle under the truck. The valve covers, timing cover, oil pan gasket, etc. were leaking profusely. The oil pan was wet to the touch. It was bad. I suggested changing back to regular old dead animal oil. Now a month later the driveway is dry again. Yes, he still parks there. So while I would not hesitate to use synthetics in a newer vehicle, changing to it can and does cause some (but not all) vehicles to develop leaks.

 

[petevandyke]

You guys CHANGE your oil?

 

[RonKMiller]

I have to disagree with Curtis. Synthetics do cause the rubber seals to be more pliable and as he eluded to, in older engines this can be an issue. Here's a case in point. My next door neighbor took his late 80s Ford pickup into Wally World and they sold him on a synthetic oil change. A week later his driveway looked like he owned a whole fleet of AMF Harleys. He had oil standing in a puddle under the truck. The valve covers, timing cover, oil pan gasket, etc. were leaking profusely. The oil pan was wet to the touch. It was bad. I suggested changing back to regular old dead animal oil. Now a month later the driveway is dry again. Yes, he still parks there. So while I would not hesitate to use synthetics in a newer vehicle, changing to it can and does cause some (but not all) vehicles to develop leaks.

I had this exact same experience with my 1988 Chevy 454 Crew cab. Although I don't shop at Wally World but DID own an AMF Harley.

 

[Rocketsled]

Based on all of the service intervals being at 6000 miles...IMHO it's not worth the headache of the math to run synthetic....dyno squeezings will last 6000 miles just fine. I'll swap the FD oil in 5000 miles or so, but only because it sat for some unknown period of time with water in it. I'll go back to a 12,000 mile interval for it then.

ETA: The problem with oil changes doesn't seem to be the oil...it's the filtration material...and based on where they decided to stick the filter...it's kinda hard to swap it without making a mess. :histerica

 

[ridinredfox]

The service manager at the new Jacksonville Motorcycle dealership says the same thing: "systhetics will leak around seals and cause damage". BS!

68,000 miles on my '05 LT. Put in 4 qts, 6K later drain out 4 qts.

Same results on my '95 Suburban. 300K, never burned or lost a quart.

Tell a lie often enough and it becomes the truth.

 

[RockMonkey]

The service manager at the new Jacksonville Motorcycle dealership says the same thing: "systhetics will leak around seals and cause damage". BS!

68,000 miles on my '05 LT. Put in 4 qts, 6K later drain out 4 qts.

Same results on my '95 Suburban. 300K, never burned or lost a quart.

Tell a lie often enough and it becomes the truth.

I can only offer what I have personally observed. New seals, weapage with synthetic, no weapage with Dino. You are more than welcome to call the shop that works on all my bikes and talk to them yourself. I can't testify to the seals being damaged on anything newer (whether it be motorcycle or 4 wheel mode of transportation, as I haven't run Synthetic in anything older than a 1998) as I have never personally seen it.
But I will testify that synthetic will leak past a seal sometimes when Dino won't.

 

[K100Dennis]

Well, here's my AU $0.02 worth on some points relevant to this thread - In industry we use Kluber products, which are full synthetics, not from mineral base oils and not containing hydrocarbons. This oil is essentially a long-chain polymer formulation, it is extremely expensive and it performs extremely well in arduous conditions. It requires the equipment to have Viton seals as it reacts badly with Neoprene, Buna N and any other organic based oil seal materials. It will strip certain paint types off surfaces. It cannot be disolved using hydrocarbons but it can be washed off with hot water. It is only used where it is required, and that comes down to special applications such as under extreme loads, in very hot environments etc. The point I am making is that if there is no (special) requirement then a special lubricant is pointless and a waste of money. In regards to seal life, with normal materials and mineral oils, 2 things shorten oil seal life - elevated temperatures and contamination (micro-abrasion). So if the temps are kept under control and the oil is kept clean there seal life will be maximised. When seals are remioved and examined, flat running surfaces and shaft grooves indicated hardened seal material which normally occurs due to excessive heat rather than chemical attack (from mineral oil). We get many thousands of operating hours from all sorts of equipment running on mineral oils.

 

[LittleJoe]

Synthetics can cause weepage on higher mileage stuff as it cleans up the crud that was preventing the leak on dino. I would not switch a high mileage component, but would run synthetic from new and continue using it.

Many hi end vehicle manufacturers use synthetic as factory fill, so not using for break in is not necessary in my books unless you have done a fresh rebuild and are doing a 500 mile breakin oil change.

If you are not breaching the limits of dino oil in your application(primarily very low and very high temp use) then the benefits of syn are not being used or needed. If you push the limits of extended drain intervals, that is where synthetics may give you piece of mind for lack of memory

 

[Rocketsled]

I have a Subaru Impreza STi that prefers Dino. There's a $0.65 seal behind $800 worth of labor* that's the culprit. Considering the severity of the job a little extra oil over it's lifetime is cheep.

* = oil pump seal...which is behind the timing belt, water pump, accessories, and acc'y belt.

 

[Zeke]

couple notes.
234k miles always synthetic, no leaks, no nothing. change every 10k.
Ok 4 notes. lol

Zeke

 

[UncleMark]

Good section on this in my book... might be worth a read to those who may have a question.

I run synth in my LT. I am now on a 9K to 10K turn for changes. The reasons are many... and greatly augmented by mechs who race this stuff for a living.

Older engines that have always had a steady diet of dino may not do well on a switch to synth. So my 95 Toy P-up stays the way it is. But Blue likes this stuff... no leaks, no drips and no problems.

 

[Rightrudder2]

Rock...That's exactly what I'm afraid of with my older LT.

Charlie...what you're saying about the molecular size of synthetics makes sense. My LT, being an '02, will probably be better sticking with the dino. I still have to wipe off a little residue from the back wheel from time to time....I think I know what's in my future but I'm not going to jump to conclusions and tear it apart right now.

new here what do you suggest for the final drive lub??? and how often do you change the final drive lub?????