15w40 HDEO in LS3?

[Peted]

What harm could be caused by running a 15w40 diesel oil in my LS3?

I currently have Delo 15w40 in the crankcase, but the engine seems very sluggish and I can hear a tick or what not and just extra noise that I don't remember hearing before.

My previous oil is M1 0w40 with 8K miles on it. I'm sending it out for an analysis ASAP. Towards the end of the OCI it felt as if it was Very thin. Hard to explain. So I believe it sheared a bit.

I have 4 jugs of Delo synthetic 5w40. I think that oil may be the best bet.

Does the LS3 have very small clearances that make 5w30 the Only choice. Or can you run the thick stuff if your climate permits? i.e. 90s every day, 80s at night.

thank you.

p.s.
I'm not sure how similar the LS engine is to Fords Modular V8, but as many know, Ford specs 5w50 for there GT500 and also the BOSS.

 

[addyguy]

In Florida, a 15w40 shouldn't hurt an LS3, but, if it is sluggish, it might respond better to a 10w30.

Delo 5W-40 is a very, very good oil - maybe use that, but thin it out with a 5w30 or 10-30? I understand wanting to use an oil you have....

 

[VR1]

Run what it calls for not that hard.

 

[Gokhan]

Shouldn't do any damage; so, don't worry. 5W-40 (fresh-oil HTHS ~ 3.8 cP) is a little thinner than 15w40 (fresh-oil HTHS ~ 4.5), about the same as 0W-40. Sluggishness is normal with increasing HTHS. Clearances shouldn't be an issue. 5w30 fresh-oil HTHS is about 3.1 and will eventually shear to around 2.5.

 

[mongo161]

I just thinned out some Chevron Delo 15w40 with some Havoline 5W-20 on sale at Advance Auto.

I made a 50/50 blend of the Chevron Delo, LE 400, 15w40 and Havoline 5W-20. I used 3 gallons of Delo and 12 quarts of Havoline for 5 Oil changes today.

IMO....15W-40 is too thick....and 5W-20 too thin for summer driving in NYC with severe driving conditions. So the blend of both oils is running fine for the summer....unscientific....yes.....but in the ballpark of 10w30.

I'm running some Rotella 10w30, Triple Protection Diesel Dino and Formula Shell Dino 5w30 in a 50/50 blended mix and my T4R is running like a champ.

 

[VR1]

Mixing oils in a LS3 Jesus,Mary and Joseph. What are you trying to accomplish by doing that? You are not only mixing different chemistries you are mixing different vicosities. I don't understand what for? I'm at a loss for words. People are so misguided these days. They here some dip that mixed such and such with such and such and the engine ran to 65 two seconds quicker lol or made it silky smooth. Jesus [censored].

 

[VR1]

IMO any oil that isn't whats on the cap is either too thin or too thick end of story.

 

[mongo161]

For some other oil changes that I did recently, using Diesel Dino in API-SM, CJ-4, 15w40 all the cars and SUV's are running fine. I've had nothing but compliments on how quiet they are running in the heat of summer.

These are ALL VEHICLES older than 8 years or older and I would not use Diesel Dino in a modern engine.

Some of the others are Mobil Delvac, Super, 15w40 mixed 50/50 with Advance Auto Synthetic 5W-20 or Mobil Super Synthetic 5W-20.

Next on board and soon up to the plate will be some Castrol Tection 15w40 and Castrol SynBlend 5W-20.


I like the qualities of the Dino Diesel for cleaning and protection and just use the Famil of synthetic or blend for a thinner oil.

 

[Gokhan]

Originally Posted By: Gokhan
Shouldn't do any damage; so, don't worry. 5W-40 (fresh-oil HTHS ~ 3.8 cP) is a little thinner than 15w40 (fresh-oil HTHS ~ 4.5), about the same as 0W-40. Sluggishness is normal with increasing HTHS. Clearances shouldn't be an issue. 5w30 fresh-oil HTHS is about 3.1 and will eventually shear to around 2.5.

Note that HTHS directly relates to fuel economy and engine sluggishness but between 15w40 (HTHS ~ 4.2 - 4.5) and 0/5/10W-40 (HTHS ~ 3.8), you shouldn't see that much difference; therefore, it sounds like you're a little bit panicky because of some minor drop in engine response.

You can also try a SN/GF-5 10w30 instead of 5w30. While they have the same fresh-oil HTHS (~ 3.1), 10w30 doesn't shear like 5w30 to smaller HTHS after driving for a few hundred miles. That way you don't sacrifice from engine response and still have adequate protection with used oil.

Another option is to go with a CJ-4 10w30 -- fresh-oil HTHS ~ 3.5.

 

[Peted]

I'm looking for a thicker oil for summer. It's been real hot in South Florida this summer. It's in the 90s everyday until it rains and cools off. Not scorching hot like out west, but hot non-the-less. I also take my car to the track and hit high RPMs on the street. I don't think the 5w30 is going to protect my engine.

I'm mostly curious if the 15w40 is going to cause any excessive wear due to clearance issue or what not. I plan on dumping the 15w40 and putting in the 5w40 this weekend.

 

[VR1]

I live in Texas and it gets pretty hot in fact the last almost month its been close to or right at 100 some days a little over that and my Jeep runs fine on 10w30 and my Honda runs good on 5w-20 neither of which show any signs of viscosity breakdown. I woudn't worry about thicker oil for hot weather thats a old wife's tale.

 

[Gokhan]

Originally Posted By: peterdes
I'm mostly curious if the 15w40 is going to cause any excessive wear due to clearance issue or what not.

I don't think there is such a thing that clearance would be a problem. That's because the oil film is much thinner than the bearing clearance.

However, oil flow would be less and your pump would be working harder and the oil temperature would be higher. These, together with the increased friction of thicker oil, could lead to a slight increase in wear -- or perhaps not. In any case, I don't think it's something to worry too much about.

 

[dailydriver]

Originally Posted By: Gokhan
5w30 fresh-oil HTHS is about 3.1 and will eventually shear to around 2.5.


^^The above is VERY highly dependent on exactly which 5w30 we are talking about.

 

[dailydriver]

Originally Posted By: peterdes
I'm looking for a thicker oil for summer. It's been real hot in South Florida this summer. It's in the 90s everyday until it rains and cools off. Not scorching hot like out west, but hot non-the-less. I also take my car to the track and hit high RPMs on the street. I don't think the 5w30 is going to protect my engine.

I'm mostly curious if the 15w40 is going to cause any excessive wear due to clearance issue or what not. I plan on dumping the 15w40 and putting in the 5w40 this weekend.



It will not cause excessive wear, BUT it is certainly NOT going to help you in either the heat resistance/anti-shear, nor the power departments (especially vs. a very good group 4/5 synthetic)!!

What is this in; an SS 5th gen, or a C6?? (I, for one would MOST DEFINITELY use a VERY GOOD synthetic in an open-tracked car [or are you talking about a drag strip??], DESPITE many on this site telling you that you "don't need it".)

If I ever get the chance to transplant an LS3 into my current ride, I would run liquid gold in it if it were available (but I would probably just use Motul 300V, or Torco SR5).

 

[hattaresguy]

It doesn't really matter what the exterior temps are, the engines cooling system if its working properly will maintain engine temps and oil temps to within a few degrees.

Manufactures also do extensive hot weather testing.

Run what the manufacture specs and forget about it.

 

[VR1]

AMEN! Hattaresguy what I have been trying to say.

 

[aquariuscsm]

You could always try a good 10W40.

 

[ArrestMeRedZ]

Or you could go with GC 0W-30, which is a thick 30 weight. I use it here in Vegas (115+ degrees in the summer) with good results in an LS1. M1 5w30 seemed to be too thin to my ears, but I get no unwarranted noises nor drop in pressure at idle with GC no matter how hot it is outside.

 

[mongo161]

That 5W-40 you have stashed should run fine in your LS3.

 

[hattaresguy]

Heavier oils than spec probably do more harm than good, they require more force from the motor to pump, thus causing more heat.

I bet a UOA would be better running a quality oil in the manufactures speced weight than anything else.