10W30 Synthetics & Consumption Variation

[LowMilesLesabre]

Yes, I used to think that was a plus. That was until I found issues with backward compatibility for Dexron 6 for my trans. Actually, this reminds me to post something on this over on the ATF forum. I guess I just wonder how much true "testing" is done when claims of back-specked fluids. Maybe they conduct extensive tests, but I found the spec lacking for the latest Dexron. Just my experience with one vehicle, but it does make me wonder.

 

[dave1251]

Originally Posted by Garak
Originally Posted by WyrTwister
We own a 2006 Buick 3.8l and if I recall , it indicated 5W-30 , but does not mention DEXOS . So far , I have used name brand conventional oil ~ 3000 mile OCI .

Technically, that's one place where GM tends to make some good sense. You call them for that vehicle, they'll say use a 5w-30 dexos1, which will be back speced for darn near everything.



It did not recommended DEXOS because this is a half decade after 2006 requirement. You will be fine using a 5W30 conventional.

 

[kschachn]

Originally Posted by LowMilesLesabre
Yes, I used to think that was a plus. That was until I found issues with backward compatibility for Dexron 6 for my trans. Actually, this reminds me to post something on this over on the ATF forum. I guess I just wonder how much true "testing" is done when claims of back-specked fluids. Maybe they conduct extensive tests, but I found the spec lacking for the latest Dexron. Just my experience with one vehicle, but it does make me wonder.

What exactly?

 

[caprice_2nv]

I've used dexron 6 in both of my 1980s gm 2004R 4 speed automatic (rear wheel drive) transmissions. They both have well over 200k miles and shifted exactly the same, (crisp shifts with no slipping) on dexron 6 as dexron 3 or the multi vehicle formulas like the maxlife I just switched to in one. I don't think it's a compatibility issue as much as a worn out transmission not liking it.

 

[Garak]

Originally Posted by dave1251
It did not recommended DEXOS because this is a half decade after 2006 requirement. You will be fine using a 5W30 conventional.

Oh, absolutely. I mean if you call GM, they will tell you that the old conventional spec (and the Vette synthetic spec) have been superceded by dexos1. You certainly don't need dexos1 in an old Cavalier. However, GM's continuity of specifications is quite clear and fairly welcome. I sure as heck wouldn't be using a dexos1 oil on anything like that, but for those that would be really concerned about proprietary specifications, that was one of GM's intentions with dexos1, to have a continuity from the old specifications.

 

[LowMilesLesabre]

I'm very glad to hear that you had good experiences with Dexron 6. In my case, I know the original owner very well and have all of his service records from day one. The transmission was never abused by him or myself. The reason I suspected that the Dex 6 was not ideal was because when I switched over to the Mobil Synthetic Dex 3 spec, the shuttering disappeared. I can't credit that just to the fact that I changed the fluid since the fluid and filter were changed religiously from the time the car was new. First and second transmission services were each at 25 k. I'm VERY pleased that the shuttering stopped. AT's work on hydraulics and so this was my guess. I realize I'm only working on a "guess" but whether I'm correct or not, the trans appears happy! I am wondering what OCI I should now allow for the Mobil 1 ATF now that I'm at 75k

 

[dave1251]

Originally Posted by LowMilesLesabre
I'm very glad to hear that you had good experiences with Dexron 6. In my case, I know the original owner very well and have all of his service records from day one. The transmission was never abused by him or myself. The reason I suspected that the Dex 6 was not ideal was because when I switched over to the Mobil Synthetic Dex 3 spec, the shuttering disappeared. I can't credit that just to the fact that I changed the fluid since the fluid and filter were changed religiously from the time the car was new. First and second transmission services were each at 25 k. I'm VERY pleased that the shuttering stopped. AT's work on hydraulics and so this was my guess. I realize I'm only working on a "guess" but whether I'm correct or not, the trans appears happy! I am wondering what OCI I should now allow for the Mobil 1 ATF now that I'm at 75k

Not very long because in about 30K miles of usage that Mobil will be very close to the CST of DEXRON VI and your theory will be tested.

 

[caprice_2nv]

I wonder if there is anything else at play here besides the CST in that transmission. I'm curious if maxlife like I used would give you similar results?

I'm also curious if I'm going to have to start changing the fluid more often again since the last change was the first time I ever went beyond 30k before a complete flush.

I guess we're off topic now though.