I've been reading some of the old SRT Engineer Chat Sessions looking for information on switching to 15w-50 Mobil 1 oil to lower oil temps/reduce friction and switching to a lower temp thermostat. Posted below are some excerpts from the SRT chat sessions that many of you have probably seen but I'm interested in your opinions. Please post your thoughts on these quotes from the Engineers:

Question:
....question about using Mobil 1 15w-50 in the Hemi 6.1.
SRT Engineering Team Answer:
"15W-50 will have a cold cranking problem at the temperature extremes we must design to. 0W-40 is plenty thick at 212F. The 0W-40 will be better for fuel economy, too. The engine is designed for it. Imagine the controversy if we required 0W-20 like a LOT of other cars... "

Question:
12-13-2006, 04:54 PM
A question about engine oil additives in the SRT's, some companies are pushing additives on the premise that there is a need to bring the oil temperature down. Can you comment on the quotes below and explain the SRT team's opinion on oil additives? a) Anytime you have oil temp over 220 F you should do what ever you can do to bring down the oil temp. b) We always target 200 F for a safe running temp. Example you add our additive and the oil temp drops from 240 down to 220."
SRT Engineering Team Answer:
"240 F is not too high for the SRT engines. We ran 167 mph for 35 minutes (until we ran out of fuel) with no oil issues.

Question:
12-13-2006, 04:55 PM
What are the benifits of the high engine temp on the 6.1? Why were they designed this way, emissions?
SRT Engineering Team Answer:
"Correct - it's catalyst temps."

Question:
12-13-2006, 05:34 PM
What are the DISADVANTAGES, if any to using a lower temp thermostat? I believe it has been mentioned fuel ecconomy would decrease. Do you see any other problems with this?
SRT Engineering Team Answer:
"This question continues to surprise me. Out in LA I was bombarded with owners convinced they had a system that was running to hot. I will reiterate - we've tested the SRT8s under the hottest conditions, harshest tracks and steepest grades to ensure it meets our customer requirements. The coolant system is rock steady for thermal. You don't want to change the thermstat. We've selected the current to meet both hot and COLD durability cycles."

Question:
12-13-2006, 05:46 PM
But many owners swear that by putting in a lower thermostat they are getting noticeably better ET times, and they have track slips to "prove it" - so once and for all, will installing a lower thermo result in BETTER ET times or not?
SRT Engineering Team Answer:
"Ask these same people a year from now after city driving and the answer may differ. SRT does not recommend any changes to Thermostat. If it helped performance without offsetting durability then this would be easy. We've never done durability HOT/COLD start on the lower thermostat temp. Therefore we won't recommend."

49 views and no one has any thoughts? Based on this, a lower temp t-stat is not the way to go. With all the folks on this board who already made this switch, I gotta believe you have some opinions. Thanks in advance.

They wont recommend the lower Tstat as they did not test for it. In a year we could all find out that we followed each other off a cliff, then again we might not and have the track slips to make us smile.

I prefer to put my trust in the engineers, and stick to the most stock/oem mods possible. Stuff like intake/exhaust, mopar performance parts, etc.

Others prefer to mod-at-risk and do their own testing. It's what makes this forum so great. Some of you buys have major balls to go tearing into your trucks! :)

But, at the end of the day I place my trust in the SRT Engineers.

As far as the oil goes there was a TSB released that recomended 15w50 in the warmer summer months and then switching back to the 0w40 in the colder winter months.

As far as the oil goes there was a TSB released that recomended 15w50 in the warmer summer months and then switching back to the 0w40 in the colder winter months.

REALLY?

That's funny, cause Milous' site does not mention this TSB???

http://www.wkjeeps.com/wk_tsb.htm

I prefer to put my trust in the engineers, and stick to the most stock/oem mods possible. Stuff like intake/exhaust, mopar performance parts, etc.

Others prefer to mod-at-risk and do their own testing. It's what makes this forum so great. Some of you buys have major balls to go tearing into your trucks! :)

But, at the end of the day I place my trust in the SRT Engineers.

I typically think your way. But all the talk and mods everyone discusses gets ya thinkin'.

REALLY?

That's funny, cause Milous' site does not mention this TSB???

http://www.wkjeeps.com/wk_tsb.htm

I believe the TSB was about the oil squirter noise in the LX cars only.

What about the SRT eng's statement about fuel economy being better with 0w-40? Could that be?

I believe the TSB was about the oil squirter noise in the LX cars only.

What about the SRT eng's statement about fuel economy being better with 0w-40? Could that be?

Correct, that was the one I was thinking of, but still it is the same motor. They wouldn't recomend it if it would damage it in any way.

http://www.***********/forums/showthread.php?t=8535

I prefer to put my trust in the engineers, and stick to the most stock/oem mods possible. Stuff like intake/exhaust, mopar performance parts, etc.

Others prefer to mod-at-risk and do their own testing. It's what makes this forum so great. Some of you buys have major balls to go tearing into your trucks! :)

But, at the end of the day I place my trust in the SRT Engineers.
Yeah, but the engineers just said they could not endorse the t-stat mod because they had not tested for it. They never said it was a bad thing. ;)

SRT Engineering Team Answer:
"Ask these same people a year from now after city driving and the answer may differ. SRT does not recommend any changes to Thermostat. If it helped performance without offsetting durability then this would be easy."

the truck's #1 selling point is its performance. a lot of thought was put into making it as fast as possible without exceeding certain durability thresholds. when it comes to engineering decisions that wouldn't have raised the bean counters eyebrows, such as thermostat temp setting, i think it's a safer bet to stick with the design specs.

Yeah, but the engineers just said they could not endorse the t-stat mod because they had not tested for it. They never said it was a bad thing. ;)

A slightly lower thermostat that lowers the coolant temps will not harm the vehicle. Period.

[QUOTE=promo718]SRT Engineering Team Answer:
"Ask these same people a year from now after city driving and the answer may differ. SRT does not recommend any changes to Thermostat. If it helped performance without offsetting durability then this would be easy."


Funny; the SRT engineers never talk about emission standards, which is one of the main reasons for bumping up temps in engines over the past 15 years. From what I've read, there is no evidence to support the loss of engine durability d/t changing the thermostat to something moderately lower (within reason), but there is all sorts of evidence to support the fact that lowering the temp improves power output!

As a side point, look at the marine industry. They are 3-4 years behind the automotive industry with incorporating the newest/best power improvements from the automotive engines (typically GM small blocks) that they convert for marine use. They are not restricted by the same emission standards, and their engines typically use 160 degree thermostats, and have much better stock hp/torque outputs than their automotive equivalents. I fully admit that these engines endure different stresses (long-term high rpm loads), but that in itself is not the reason for running a cooler thermostat (I can run my boat at WOT for hours, and never exceed 160 degree temps)

All I'm trying to say is if you want to try the lower temp thermostat, then do an oil analysis with your normal oil change prior to the thermostat change, and then another one with the lower temp thermostat with the next oil change (using the same motor oil and relatively similar ambient temps, btw). If the analysis doesn't change, then I'd say the SRT engineers were not being totally honest about this subject.

If you think that I'm being unfair about the SRT engineers "word", then consider the fact that we were "promised" a tow hitch solution by 3/06 (and many dates thereafter) What's the latest excuse you've read about that??
They are constrained by all sorts of issues that we don't have to deal with. It's up to us to make reasonable decisons based on the evidence available to us, though we all recognize that we take on some risk in the process since its unproven in our given situation.

Just one persons humble opinoin on the matter.

I realize that the only thing we have to go off of is the engineer's suggestions, but I don't see DCX employees giving us the ok to mod our vehicles without factory authorized parts, wether it will hurt us or not. It's in their best interests to disclaim those mods to protect their warranties.

P.S. I would have done a before and after oil analysis, but I already changed thermostats and I'm not changing back just to do that. :)