Member
When I bought the Z (4yrs/50kmi ago), the very first maintenance I performed was to replace the old (lifetime) trans oil with AMSoil synchromesh trans oil - and doing such was a HUGE improvement, in that initially it had shifted like something out of a 60 ton truck, ie, not pretty, and probably the most cumbersome shifting I could remember fromover the last several decades... and maybe this wasn't surprising in that what came out looked like burned pine tar and had the viscosity of molasses in February.
I think the AMSoil has performed well since then... and I think over and above providing reasonable lubrication to the inner workings of the trans, it also dissolved the varnishes that had built up in the trans over the previous 130k miles, ie, over the next 500-1000ish miles the shifting went from hugely improved to silky and sweet (where it stayed).
But there was a "problem" in that the shifting in the winter, when the overnight temps dripped into the 20s, in the morning was stiff. Not terminally stiff, and not something that didn't improve with just a few miles of driving (back to silky and smooth) - but stiff.
But as has been pointed out in this forum multiple times of late, the AMSoil has a higher viscosity than the oil spec'd by bimmer. So, with 50k mi on the AMSoil I decided to not only swap it out, but to try something that was closer to spec, and what seemed to have a positive following here: Royal Purple Synchromax... which I did mid-week last week, ie, have now a week's worth of driving on it [also of note: the AMSoil when it came out, flowed like new AMSoil, and although no longer looking like new oil - somewhat darkened - was still transparent.]
What have I observed: the stiffness in the morning is basically gone - I'd say that the shifting force and smoothness while cold, is on par with the AMSoil hot; but the shifting at temp is no where near as smooth as the AMSoil. To the point that I think I'd rather put up with the stiff shifting while cold (which only lasts a few minutes), vs, the crunchy shifting with the RP. ... but at $35 for the 2 quarts, I don't think I'll dump it immediately - but if I can convince myself that the AMSoil was as a lubricant not failing the transmission, I'll swap back to it once the weather warms up (May or so), and just stay with it.
Thought the question of the AMSoil failing the transmission is a serious one - although used 250Gs aren't that expensive, they are a pain to replace, and I guess there is the philosophical/ethical question of not wishing to abuse things mechanical... so: was the stiff shifting harmful to the trans??
My guess is not. My impression is that all the bearings in the trans are open bearings, and clearances within them aren't so tight that the RP would get in where needed but the AMS not. My impression is that the place one notices the stiffness is: the oil film on the syncro cones and having to clear that off during the shifting process (getting the shaft and gear to speed match), and the more viscous when cold AMSoil is what's interfering with that process... and once it's up to temp it does get out of the way per spec.
On the flip side: although the RP is less viscous and gets into the interstitial spaces more easily, my impression, from the crunchiness (admittedly highly technical term) I feel is that the AMSoil has longer/tougher polymer chains, which are protecting mating surfaces, but the RP with is lower viscosity is either dripping of these surfaces too quickly, or the chains aren't up to task [kind of like MB gracefulness vs Dodge Dart three-in-the-tree functional].
So: if I can convince myself that as far as the trans is concerned the lubricity of the AMSoil is adequate/sufficient/appropriate, I'll be moving back to it - I do miss the silky shifting of the past n years. If those in the technical know can offer insight into the question: please do so.
For those in colder environments - I suspect the RP, or ATF are more appropriate products, but for us in the only marginally cold winter climes: the AMSoil might just be an appropriate choice.
In trying to understand the shifting process within the trans I've come across a paper and an illustration that might be helpful to others:
http://publications.lib.chalmers.se/...594/179594.pdf
http://www.rsgear.com/media/7177/syn...eps-detail.png
Member
I don't think the higher viscosity of AMSOIL does any harm. Although the RP Syncromax shifts OK for me, I have not compared the two fluids like you did. Others who have, say the AMSOIL is too hard when cold, but I don't drive much when it's cold. All the raves about AMSOIL and now your comparison, make me curious to try it next time I change fluids.Originally Posted by gmushial
BMW MOA 696, BMW CCA 1405
Member
I just changed out the factory fill at 28K miles and replaced it with RP Syncromax. I can't say that I love it- feeling the crunchy shifts when they are on the rapid side. Hoping that perhaps with a few hundred miles and a CDV delete things might improve. If not, I was thinking of switching to Penstosin LTF-II. (I have a half gallon of LTF-III if anyone in the LA area wants it)
Member
One thing I'm wondering is: is it possible that the 250G and the 320Z have different preferences? It wouldn't be the first time: the Muncie from the original GTO had one set of preferences; while it's stablemate the T-10 had another; and likewise its replacement the super T-10... so, I'm wondering if we shouldn't be keeping clear which trans we're talking about. ... but with another 40 miles on the RP today, I'm starting to think that maybe I won't be waiting until summertime to go back to the AMSoil.... really don't like the crunchy feeling - maybe the RP allows the synchro cones to shed the oil film faster, but the feel has me concerned that it isn't underserving the rest of the trans components?
Member
I think they have the same viscosity. No point in doing that.
As for rapid shifts, I have never done that on any of my many cars. To grasp the knob and ram it through the gate into upshifts -- never. Yet, I have been with many people who drive that way. They are insulted that I would disapprove.
I shift deliberately in two distinct steps, move-move. One movement into the middle of the gate, the next into the gear. No crunchies.
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I think all the stock viscosity fluids (BMW, Pentosin, RP) serve the gears and bearings as designed. The higher viscosity AMSOIL maybe feels better because it stays on the cones longer during a shift, and might provide even better gear lube. It's just harder to shift when cold.
Last edited by Vintage42; 01-15-2015 at 08:29 AM.
BMW MOA 696, BMW CCA 1405
Grumpy
BMW CCA Member
The Getrag and ZF may well have different tolerances. I know the 420G is different than the 320Z.
Nice find on that thesis. It's the first time I've ever seen that all in one place, with a bit of supporting math. The "double-bump" he describes, where the blocking ring is broken loose and the gear turned, is what I suspect is behind some of the "notchy" complaints. What I feel sometimes is like a crunch, except it's but a single tooth.
/.randy
Member
I would love to have a Muncie 4 speed with Hurst Syncrolock shifter behind my BMW engine, would take it over a BMW 5 or 6 speed anyday,
they were sweet shifting with that Hurst and type of oil hardly matered. --What Amsoil are you talking about, the MT 5-30 or their higher viscosity
transmission oil, some get the two confused.
Member
I changed mine with Pentosin MTF. I don't know what was in it before but it did come out clear and clean. It previously felt notchy and hard to shift. It feels great now but it did take a few weeks to get to the current feel. I ordered it on Amazon and the price was reasonable plus it shipped to the house. At the same time I ordered Mobile 1 75w-140 for rear diff. The diff was really howling at certain spreads and all the noise is pretty much gone now. I did go to the local Oreilly and they had the other options but I thought this was a good choice. I could not purchase these oils local for anything reasonable. 2001 with 122k.
Member
That might be a description of what I'm feeling... any suggestion of why it doesn't appear to be there with the 15% higher viscosity lube? Maybe Vintage's suggestion? ... but bigger picture: is the AMSoil underserving the mechanical systems of the trans because of the higher viscosity - are the bearings not being properly lubricated (given you understanding what's in the box), ie, the smoother shifting might be hiding other evils? Or even possibly again per Vintage's suggestion, that in fact it might be doing a better job than the bimmer spec oil, ie, by simply having a higher shear strength/longer chain molecules (isn't that what viscosity is really all about)? ... the thought I'm coming to is: maybe the trans is really better served by the AMSoil, and the winter stiffness is more of an inconvenience than a tattletale sign of something detrimental happening? Even if you don't have definitive answers, care to share your thoughts and what one might look out for/notice? Though I note that you've stayed with the ATF viscosity - is that simply because that's spec, or is that possibly out of concern of under-lubricating the trans and hence shortening its useful life?
ONLY BMW Content is +
Moderator
FWIW, I went from whatever was in the car when I bought it to RP Syncromesh to Amsoil and had a noticeable improvement each time. The Amsoil has been in for about 30k miles now. I'm sold on the stuff.
T
Stuff. I got stuff.
Member
I have tried both RP and Amsoil in both transmissions (318ti 250G and Z3 3.0 320Z).
The 250G was as you describe, amsoil is a bit stiff when cold but shifts nicely when warmed up. RP was "crunchy" and got worse with time, I drained it after 15k miles and it was the consistency of water. I have run amsoil in that transmission for the past ~50k miles and had no issues. Changed it two times at 20k mile intervals and recently changed it at 10k because I started doing more track days. Every time I've drained it it has come out the same consistency that it went in just looking a bit dirtier.
Last year, shortly after I bought my Z3, I decided to change the trans fluid. Previous owner claimed redline was in there but wasn't sure what weight. The car didn't shift as smoothly as my 318ti, part of that was worn shift linkage bushings and part was "crunchy" gear engagement. For peace of mind I decided to change out to the trusty old amsoil synchromesh. The car immediately shifted worse. Going into all gears when cold was difficult and it caused 5th gear to start sticking. It freaked me out enough that I changed out to RP within two weeks just so I could have a fluid that more closely matched BMW spec. Difference was again night and day. The RP cured the 5th gear stick and shifting was much better when cold. Once warmed up it did have a slightly "crunchy" feel but that actually seems to have gotten better over time. I'm going to change the fluid at an earlier interval, probably 10k, but put RP back in.
The only thing I don't like about my Z3 data points is that I when between three different fluids within a two week period. Maybe the amsoil would have "broken in" some more but I didn't really want to chance it. We'll see what the RP looks like when I change it out again.
11 128i Space Gray slicktop
13 WK2 Deep Cherry
Member
The Muncie in the goat even with the factory Hurst was truly sweet... actually probably my standard of how a transmission/linkage should feel/shift [the trans/shifter in the Fiat 124 '73 was equally sweet, but fragile as all get out]. ... them were the days... and sold it for $800... if I only knew. and: MSTF 5W-30.
Member
ok ok ok
this thread is comparing RP Syncromax to Amsoil? not only should we clearly define the trans but how about the amsoil product too.
Manual Transmission,S5D320Z (5-SPD)......GLS [2]
All TEMPS......
No AMSOIL Product Recommendation
When I changed all of the fluids in my ///M Roadster I used RP Syncromax because I never found a definitive answer as to the amsoil product I needed to order.
Grumpy
BMW CCA Member
My Amsoil experience from several (>5) years ago is like Dave's. Shifting got worse, hot and cold. I lived with it for a few years, until I finally decided to dump it in favor of ATF. Same thing with the new coupe. Right after I bought it I dumped the "new" Amsoil (or so I was told) for cheap ATF with a noticable improvement.
My single tooth notch is there cold, and goes away hot. After that thesis, I'm starting to put more relationships together. What I'm currently mulling over... the lighter oil is allowing the blocking ring to wedge on tighter. Or, the thicker oil is supplying more drag due to the pumping action as the teeth mesh, helping free the blocking ring.
I'll probably have a different theory tomorrow.
/.randy
Member
Terry - I wish I had your "cold" winters... but if I did, then there wouldn't be a choice: it would be the AMSoil... and it may just be again soon, where I simply baby it for the first couple miles/dozen shifts... again, I probably should give the RP a chance, a la 500 miles or so, and see if it improves like the AMSoil did originally... but short of either some significantly colder weather [though I don't remember the AMSoil being any worse in single digit temps than at 30F], or the RP starting to feel a whole lot better... or RandyW jumping in and suggesting that the AMSoil is damaging the trans, that's where I'm heading back to... though just maybe with a quick side trip via Pentosin just to compare.... though as I've posted before: for those in truly cold country, I'd simply go the spec viscosity route - it's only us in those transitional areas that have to worry/choose which lube.
Grumpy
BMW CCA Member
Just dawned on me. Didn't Kelly (2Kred) have a 2.3? If so, he had a 250G... and what Greg is saying would go a long way toward explaining the difference he and I saw.
/.randy
Member
I think some time ago, a la above, I suggested that we needed to specify which trans any data pts involved; likewise the RP was specified in the initial post, and the AMSoil in the post above.
And yes, what AMSoil says on their website is part of the problem - they appear to recognize that their MSTF 5W-30 is some 15% higher viscosity than what bimmer specifies, hence why they have no product to recommend... but we that have tried it anyways (nominally on the recommendation of others) have found that in specific conditions/temperatures/climates, it seems to work quite excellently. ... now, at least in my book, the question is: is that sweet shifting, masking damage being done?
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As in the ring is able to shed the lighter oil more quickly, hence the tighter wedging? Conversely, with the heavier oil, the engage is slower, but the disengage is quicker?
ONLY BMW Content is +
Moderator
To live where you live, I'd gladly accept some cold weather. If the RP is in, yeah, leave it in for awhile. I loved the stuff, it was only when I moved to Amsoil that I noticed even smoother shifting.
Member
Thank you gmushial for posting this fascinating read and visual aid. I now understand exactly the feedback that I am feeling in the gearbox and have a renewed confidence that the every once in a while crunch is merely just a single tooth click, completing the shift, and away we go..........
Member
Has any of you tried mixing an additive? I'm thinking of mixing Amsoil/Royal Purple with LiquiMoly anti-friction gear lubricant. I'm thinking maybe this would help with Amsoil's cold morning shifts dilemma or help with Royal Purple's viscosity a little.
I just have to find out if the 5 speed getrag needs friction on its synchronizers thus maybe not a good idea.
Member
Totally lacking the experience and expertise of others on this thread, I have a couple of observations after reading all of the above. Whatever was originally in the OPs tranny came out like pine tar colored molasses, so was less than ideal. For 50k miles on the Amsoil replacement, the tranny worked perfectly when warm and nothing has failed. If it were causing any damage at all, shouldn’t that have come to light by now? When you drained that oil, it flowed like the day you put it in. Another testimony to its quality and longevity. The slight discoloration was probably caused by the flushing out of the original pine tar colored residuals of the previous oil.
If the Amsoil shifts smoother when warm and there are no signs of damage after 50k miles, it appears to have been an excellent choice. I changed all oils to Amsoil when I purchased my Z3, 1000 miles ago based on recommendations on this forum and glad that I did.
Excellent posts by everyone. I feel that I never stop learning things here.
You can’t have everything. Where would you put it?
Jbird
Back in the day we used redline mtl then on a whim we tried the current bmw trans fluid and it worked great and improved cold shifting a lot
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