SSO RPM's drop ...

Ndx

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Hi Guys, I switched to SSO 0w30 In My Mazda 3 2.3L ( Spec. Oil is 5w20 ) I Noticed after switch that my RPM's are lower at 100Km speed... Before needle was on 3K rpms. now Its under 3K rpms. you can see it with out problem ... Beside I have scangauge II .. Why is that ? I was running ASL 0w20 .. Didn't notice any difference! I was sure when I switch to 0w30 my rpm's would jump .
 
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JHZR2

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you must have an AT that is slipping. Mechanically coupled systems cannot change speeds without something slipping, or a ratio changing.
 

Ndx

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Well AT was replaced less then 8K Km agoo .... With brand new unit from Mazda ... So I really don't think so ... Maybe ... I hope that's not a problem ..
 
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i would think if the tranny was slipping the RPM's would go up not down? i myself just switched to SSO OW-30, i did the atf and the rear axle also, and i have noticed a mpg gain on my scan gauge not a huge gain but its keeping more of my money in my pocket
 
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 Originally Posted By: D189379
There's is absolutely nothing that your engine oil can do to make this happen. Seems like an issue with your transmission.
+1
 

JHZR2

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yeah, a slipping AT would go up... I guess my point is that I do not see how the RPMs can change on a mechanically coupled system... The tires rotate once for every n rotations of the transmission, which rotates once for every m rotations of the engine... It is pretty set, unless something like slippage, a change in tire circumference, etc. has changed, which would effectively vary the ratios.
 

Ndx

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So is it AT ? Because now im confused ? Some people say that IF at slipping they RPM's should go up ... Others saying that it is tranny problem... What about if I added 2 more PSI to my tires ?
 

Ndx

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OK :) So we know its not my AT because RPM's dropped ... They did not went up ... Over inflated tires ? I added 2 extra psi... ? Something wrong with my engine ?
 
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maybe the tire dont rotate the same speed that it was before. If you change size and diameter of the tire by over inflating or whatever you do with the tire itself or just changing brand, there could be a difference with the speedometer but not the rpms. During summer time with original tire from factory at 100 kph, the rpm is at 2050-2100 rpm. When I put my winter tires with rims, at 100 kph, the rpm is at 1950-2000 rpm.
 
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Could it be before the RPM's were being looked at without the transmission in Lockup mode (cold tranny) and you happened to notice it now in Lockup mode?
 
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 Originally Posted By: Ndx
What about if I added 2 more PSI to my tires ?
If this increases your wheels' circumference, nothing on your instrument display will alert you to a change... but you'll actually be traveling faster at an indicated speed/rpm than you were before you pumped up the tires.
 

Ndx

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So I dunno :) Just weird I hope that my car will not die anytime soon ...
 
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I've noticed this phenomena myself, but it didn't last for more than a day after the new oil was installed. I would suggest a theory, but I would be attacked and then banned.
 
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 Originally Posted By: StevieC
Could it be before the RPM's were being looked at without the transmission in Lockup mode (cold tranny) and you happened to notice it now in Lockup mode?
I second this suggestion. How far is your normal commute? If it is short perhaps the transmission never got warm enough to engage the TCC during cold weather, but with the arrival of warmer weather the transmission warms up much sooner. Example, my transmission TCC will engage about two miles after a morning start these days, whereas on a cold winter day it will take more than five miles of stop and go for the ATF to reach the same temperature.
 
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