new Ride-1993 K2500 w/ 7.4 (454)

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bbslider001

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Hey guys. Well, I picked up a new ride last week. A '93 K2500 Suburban with a TBI 454. It rides and runs excellent. So, long story short, I have already been thru it front to back and changed all the fluids. The PO has been using Delo 15w-40 on it for the last 30k miles since he owned it. I personally want to go back to 10w-30 that is recommended, but I wonder if going back to lighter weight affects anything?

Currently, on this change, I filled with Supertech 15w-40 and a quart of MMO for a light cleaning. It didn't really seem to need it, but figured it couldn't hurt and I got 8 quarts of the stuff for free! I am diesel educated, but the gas thing is a little new to me. I'll probably go with Rotella 10w-30 if the change over makes sense.

Thoughts? Input? Knowledge?
 
Just another internet opinion although I have more than one big block in my household.... in So Cal that 15w-40 is an excellent choice and I'd stick with it. The 10-30 isn't going to gain you anything even though it won't hurt anything either.
 
Originally Posted By: dnewton3
10w-30 would gain fuel economy, without risk of additional wear.


While I certainly defer to your experience, a change in oil weight will not change the fuel economy of a mid nineties 454 in a 3/4 ton 4x4 truck enough to notice.

If there is any oil consumption issues at all it has been my experience that the 15w-40 is the better choice. Like I said though, it's just my internet experience and your opinion is just as valid.
 
I agree with both opinions on different fronts. I did have a guy give an interesting point of view. He has built about 500 (his words) 454's in the last 20 years and done many different versions. He said that this particular engine runs best at 2000 rpm with minimal friction and that heavier oils tend to take its efficiency. Again, I am just trying to get educated and I am not going to lose sleep over 15w-40 vs. 10w-30. I am just curious and wanting to do the best for my situation. I am thinking that 15w-40 isn't necessary where I live just due to the fact that we don't have heat extremes, nor cold extremes. I can get Rotella 10w-30 readily at my local W-Mart and I like the idea of staying within specs.

My main question still hasn't been addressed though. Will it be harmful to go to lighter weight after it has had 15w-40 for the last 30k miles? I have heard differing opinions on this. Dave? Greg?
 
Quote:
My main question still hasn't been addressed though. Will it be harmful to go to lighter weight after it has had 15w-40 for the last 30k miles? I have heard differing opinions on this. Dave? Greg?


Moving to 10w-30 should not be a problem. If you find that it consumes more oil than you are comfortable with, you could always give 15w-40 another try down the road.

Don't expect any measureable change in fuel economy between those two viscosities...454's are thirsty, and there is no getting around it.
 
Yeah, I am not worried about fuel economy. I mean, it's a 454 after all. My hand calc's are getting me 12.5 for the first tank of fuel. I got a good one I guess?
 
Originally Posted By: JHZR2
I think the rotella 10w-30 is a great choice.


Agreed. My dad had a 1974 GMC with a 454 he bought brand new. He didn't use HDEO, mind you, since that wasn't much of an issue at the time. He certainly only used 10w-30 and stayed away from thicker oils.

The body rusted out long before anything could possibly go wrong with the engine. If I recall correctly, it rusted to pieces before two severe service OCIs were done.
wink.gif
 
Originally Posted By: cowhorse01
My main question still hasn't been addressed though. Will it be harmful to go to lighter weight after it has had 15w-40 for the last 30k miles? I have heard differing opinions on this. Dave? Greg?


No it will not.

The anti-wear attributes of lubes are moreso affected by the tribochemical barrier, moreso than the viscosity. This is borne to be true in the SAE study 2007-01-4133 and also can be seen in my UOA studies.

As for the fuel economy, 10w-30 most certianly will improve fuel economy in this application versus the 15w-40. Now, it might be very slight, and perhaps difficult to quantify, but it's there. Viscosity is the resistance to flow. Thinner fluids are easier to pump, period. Less power needed to pump thinner fluids will result in less fuel consumed to achieve any load satisfied. I do agree it will be hard to see, but it's there. The thinner fluid might equate to a 1.5% increase in fuel economy. If the 454 is getting 10mpg, then you'd only see .15 mpg increase. Since most folks cannot track fuel that accurately, you'll likely not see it. But I cannot see the tiny atoms in molecules either; that doesn't mean they're not there ...

Genearlly, neither fluid is going to help/harm the engine. One might be able to help your wallet, but it would be hard to distinguish at times.
 
Good deal then. My next change will be Rotella 10w-30 and a good filter. I'll be doing 5-7k mile change intervals most likely, no UOA's. Thanks for the input!!
 
Dave or anyone else, I only saw 10w-30 Rotella in a syn blend. Is this the only one available in Rotella? The website didn't give me any answers. I don't have a problem with that, but I thought there was a purely conventional one available.
 
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There is a dino 10w-30 Rotella, but it's actually more difficult to find than the T5. It is starting to sprout up at a few places; I've seen it on the shelf at OR's last summer. But generally, it's not common.

The T5 has been nearly the same cost as the dino Triple Protection, so there is no reason not to use it. WallyWorld has it for less than $13/gallon in several regions.
 
I did find it at O'Reilly's for 17.88 per gallon, but that is CA prices. WM only has the syn blend but it is only a dollar less, so I guess the dino will be my choice. Thanks for the info!
 
I have a 92 C3500 with the same 454 TBI engine. Although I also have a supercharger on mine (Whipple). 12.5 mpg is about good as you can expect, my truck gets about 12 at 75 mph, and a lot worse in town. Pulling a std car trailer with a regular vehicle on it, best is about 9.5 mpg.

I have been using the Rotella 15W-40, with additional ZDDP supplement since it has the flat tappets. So far good results, although I have not done any UOA. I drive the truck so little anymore that my results would not be significant, I change it at 3K.

I believe the factory spec is 10W-30. I have been running the 15W-40 diesel oil for years now.
 
Factory spec is 5w30..


at least for my '99 3500,these trucks don't need that heavy of oil i don't know why everybody thinks they do mine lives on a diet of 0w30 and 5w30 and she tows heavy loads regularly,so unless one has a OP issue 5w30 is what to use,mine has great oil pressure 75psi cold and 60 hot so i wouldn't think of using a thicker oil,the TBI motors were terrible on fuel the 96 and up Vortec were lil better and improved power,i can achieve 14 with mine with 4:10's running it easy.




http://img.photobucket.com/albums/v94/daman1/RV.jpg
 
Well, a little update. I am running the Rotella dino 10w-30. My local OR carries it and will price match for Wal Mart's syn blend, so I'm good to go. I have still been getting about 11.5-12.5 mpg, os no complaints. I simply love this truck. It is dirt reliable, simple to work on and cheap for parts!! I can't complain.

I have been away from gas for awhile, but am really enjoying the less maint. for my wallet and time.
 
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