I know I am beating a dead horse here but I would really like to quiet down my LS1. I have piston slap and valve noise. At startup I have piston slap bad it sounds like a duramax, then when it warms up that goes away but then I can hear the valvetrain sewing machine. This is on M1 5w30 and a Napa Gold filter ie wix. So I work in the parts room at a car dealer and we sell Castrol so I special ordered a case of German Castrol 0w30 and from reading all the threads now im worried it will make my car louder which I don't want. So ive been considering just putting in either 5w30 GTX dino oil or 10w30 GTX. I run 5w30 GTX in my 6.0L 2002 2500hd and it doesn't slap at all. So I would like some opinions on what to do. Thanks! BTW, Im switching to the bigger truck oil filter to.
Who knows if it will help or not. I don't really see engine oil that is good for lubricating helping quiet piston slap since that has to do with the difference in expansion of the blocks and the pistons and their geometry.
For valvetrain noise it depends. If you valvetrain is noisey because your oil is too thin it might help... if it is loud bc the lifters are bad, a pushrod is bent, or whatever else it might not help.
If you look at the product data sheets... you would find that Castrol doesn't list GTX's specs for HTHS which is practically the most important number to compare for lubrication at operating temp. Kinematic viscosity is easy to perform in the lab, but the actual data is only marginally applicable to an operating engine. They also don't list kV at 40C... Oh well:
Castrol Syntec 0W30
HTHS: ? but believed to be 3.5
KV @ 40C: 72
KV @ 100C: 12.21
At any rate, without knowing for sure since Castrol doesn't want to release any decent data, I would imagine that the GTX dino oil has less operational viscosity than the Mobil 1 5W30 that you are running. Mobil 1 is usually commented on as being very light, but in fact it was reformulated a few years back and the viscosity numbers are a little higher... this does not mean that it doesn't shear, just that it isn't all that thin as some people make it out to be.
As far as the GTX specifically, I don't know what their target for HTHS is or what that number is. However, VII's (viscosity index improvers) usually increase kinematic viscosity somewhat disproportionally compared to HTHS. So if they were using the same chemistry as Mobil 1 I would assume it has less HTHS since the kinematic viscosity is also lower. Alternatively, if you look at the 5W30 versus 10W30 GTX, the 5W30 has a higher 100C kV... likely due to a similar HTHS goal and the need for more VII in the 5W30. All that being said, synthetics with decent base stocks don't need as much VII as conventional anyway so I would assume the Mobil 1 has more operational viscosity and a higher viscosity index.
As far as the Castrol Syntec 0W30 (German Castrol), it is in fact thicker than most of the off the shelf 30's that you get in the US. To the topic at hand, it might help you. If you were coming up on an OCI and already ordered it, there isn't anything to be hurt by trying it out. It has had very good UOA (if you believe in them ) and has been run in many LS1's with good results. I wouldn't personally try out the GTX for what you are describing.
Well I went ahead and tried the german castrol 0w30 and so far its great. I dont know if it was the mobil 1 5w30 or maybe the filter was bad but the car is alot quieter now. It still has piston slap but its faint not obnoxious like it was before. Still has a little valve train noise but not much, doesnt sound like a sewing machine like before and the more I let it run the more it seemed to go away. The mobil 1 only had 500 miles or so on it but ever since I put it in the car sounded like it was coming apart when cold, it did this with the previous oil too but I just bought the car and im assuming that was mobil 1 to from the m1 filter on it when I bought it.
Doesnt surprise me that you have loud valvetrain with Mobil 1. Like i mentioned in the other thread, it seemed as though the people who had all the oil consumption, valvetrain noises were running Mobil 1...
Fyi, i run castrol syntec 5w-30 and have not had any oil consumption issues, valvetrain noises or anything. I even ran regular castrol GTX on my old 00 Z and never had any problems.
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I recently switched from 5w30 castrolsyntec to 10w30 castroledge (think it replaced syntec) and it made a huge difference.
Basically. They brought out Edge which was supposed to be a tier above Syntec, but then they redid the additive packs and made the whole line Edge but split between "Edge with Syntec Power Technology" and "Edge with Titanium Fluid Strength Technology."
In the release for those they mention the 0W30 product specifically and mention that it was not going to be changing so that it continues to meet all of the Euro specs. It goes on to say that they will change the name when they get OEM approval, implying that the 0W30 won't move to the Edge base-stock or even the additive pack. This isn't surprising since the 0W30 is a "full synthetic" in the European sense (Group IV - PAO) and almost all the off the shelf synthetics are Group III in the US ever since Mobil filed their infamous complaint with the National Advertising Division of the Council of Better Business Bureaus against Castrol for calling a Group III a synthetic and the NAD ruled in favor of Castrol... at least on that particular item.