Elevated titanium is valvetrain. The elevated iron is peculiar. Where’s that coming from?

 

i find it fascinating that no make-up oil was added over what I find to be an excessively long oil change interval...although oil still seemed to be ok, kinda...
as an aside, I understand average values from Blackstone are for oil used less than half that interval...some being garage queens, some being track cars. So there's that too.

Maybe pull plugs, see if all look same. Not sure if octane booster is being used...it will discolour plugs (reddish). I presume engine doesn't feel like its lost power (yet?) or making any new untoward noises.

Either way, i'd treat a LS7 with some 'better' oil...like Redline 0w-40 (1200ppm zinc) or Mobil1 0w-40 FS Euro spec (1000ppm) at the very minimum and change more often, Don't worry about fouling cats...there's not enough zinc in there. moreover, any slight contamination cleans off when they're super-heated (track)

Good luck

 

I have not been using any octane booster. The only additive has been occasional Lucas injector cleaner added to the fuel.

The 4500 miles were mostly moderate driving, but that will change. My intent going forward is to use this primarily as a track day car, including drives to and from the track (200 miles round trip). So I will plan to change the oil at far fewer miles based on the more severe use. Maybe I’ll do 1000 miles and another used oil analysis to see what it shows. If I have a significant problem, I assume it’s cheaper to address it sooner rather than later.

So far I have not noticed any obvious loss of performance or strange behavior. I did however notice what seemed like a lifter tick on the first start after changing to the thicker oil. After the engine ran for a while and reached operating temperature, the noise was gone.

 

4.7 mpg was what I saw, and 245F oil temperature

 

Could also be rods, another known issue.

 

I agree on "fixing" LS7 heads. Some can be near perfect, some will never be close to right. If I were a young guy again, I'd be calling Tony Mamo for a set of his aftermarket heads. They offer superior flow with a smaller port. This is analogous to installing a smaller garden hose, but getting more water thru it. My .02....

 

It’s an interesting comparison, and Tony definitely does great work focusing on port velocity—which is exactly where the 'garden hose' analogy comes from. However, there’s often a misconception that a smaller port volume is the only way to achieve high airspeed.

The reality of modern port design is about efficiency, not just raw cc numbers. For instance, our Archangel heads utilize a 275cc runner, but because the port geometry is optimized, the intake airspeed is actually higher than many smaller 265cc offerings while moving significantly more volume. You aren't just getting a 'bigger hose'; you're getting a more efficient one that maintains higher velocity across the entire lift curve.

At the end of the day, the results on the tarmac usually settle the debate. The Archangel heads currently hold the world record for the fastest naturally aspirated, stock bottom end, 427ci C6 Z06 in the quarter mile. When you can move more mass and maintain higher airspeed than the 'small port' alternatives, that’s where you find the ETs that set records.

https://americanheritageperformance.com/

 

It would be very interesting to see a flow chart showing CFM flow and velocity at different rpm's. Especially focusing on those specs up to 6,000 rpm. @Tony @ Mamo Motorsports

 

"Grinder11" gets a Monday afternoon "Beacon of Reality Award".

 

Ti is valve train? I would think rods would be implicated, so more info would be interesting to me on that source..

I think lifter tick when starting is super common. I really don't know what to make of that in my car.

I have had the heads done and Ti exhausted valves put in. I had valve wiggle test and micrometer confirmed valve issues that were dealt with - under warranty even, but by a local machine shop for the dealership. The valve guides I believe are powdered metal stock and would raise Fe?? Not sure. But could be one source of Fe (valve guide s failing due to concentricity issues). I think the Ti valve guides are brass now on my car.

This thread makes me want to do another uoa on my car. But I only change oil every 2 years now. I have never done a UOA on any car and had the oil look to be "spent" (mobil 1)). I have gone 5K while tracking some as well, and the oil, while not free of metals of concern to some degree, was always within spec and not contaminated. I realize 2 years is not what GM recommends, but 11Qt of 0w-40 run for about 3K tops, not on track is just overkill to change sooner in my opinion.. Especially when it looks clean and like I said the UOA doesn't show any degradation.

What I am saying is if you change oil every 500 miles you will have 1/6 as much metal values as 3000 mile intervals, that's basic math.. But the oil could be fine at both intervals.. Many metals are even considered lubricants! So if the oil is within spec (BN, vis, no contaminants) I just don't know why more frequent oil changes would do much. I agree with 0w-40 for track. I only run 0w-30 because I don't track and live way north. My oil hardly ever gets above 200F!

 

Some comments...

53,000-mi on the engine and 4500-mi on the oil. Ti (10 PPM), lead (23 PPM), and iron (84 PPM) are all high, considering only 4500-mi on the oil. Key sources of iron can be ring faces, bore walls, valve guides (if there is a valve-head-to-seat concentricity problem), cam lobes, and exhaust valve stems (if there's a concentricity problem). Lead is almost always from bearings, from leaded fuel, or some brands of octane "boosters". Ti (titanium) is either from the sides of the connecting rods' big ends (most likely) or from intake valve stems (if there is a concentricity problem).

High wear rates occur when two Ti surfaces rub against each other. To prevent that, the GM supplier that manufactured LS7 connecting rods developed a Chromium Nitride (CrN) coating for the rods; however, the coating was not robust enough, so in some engines, the coating wears off the sides of the big ends. In cases of failed CrN, microscopic Ti dust gets in the oil, and some of that cannot be filtered. Ti dust is super abrasive, and when it gets in the oil, it is likely to increase wear of many internal engine parts.

With your high Ti, lead, and iron, I think there's an engine overhaul in your future.

Mobil 1 5W30 is **** oil as far as I'm concerned. In re: engine oil marketed in the U.S., there are two meanings of the word "synthetic", the scientific and the legal. "Standard" Mobil 1 products use a type III base stock, which is not really synthetic. It's highly refined (as in "hydro-cracked) crude oil. That said, it's legal to call type III based engine oil "synthetic" because of a lawsuit filed years ago against Castrol by Exxon-Mobil which claimed Castrol's "Syntech" was not synthetic because it had a crude oil base. Sadly, Exxon-Mobil lost that court fight and since then, tons of refiners and blenders of engine oil market their type III based productsl as "synthetic" even though they are not synthetic.

Now, the good news for M1 fanboys and fangirls is that some of the other, higher-end M1 products–the ESP and Supercar lines–are a combination of polyalphaolefin (say "poly-alpha-oh-leh-fin) or "PAO" (Group IV) base which is manufactured (ie: it's truly "synthetic") from ethylene and polyol ester "POE" (Group V) base stocks which are made by an esterification process where a polyol reacts with fatty acids in the presence of a catalyst and typically at high temperatures.

Red Line's line of "High-Performance Engine Oils" all use base stocks that are a mix of PAO and POE.

For any Corvette Small-Block V8 other than the Gemini engines, 0W40. Mobil 1 "Supercar" is good, but I think Red Line 0W40 is better because of its unique combination of base stocks and additive package. For the Geminis (LT6 and LT7), M1 5W50 is a good choice, but Red Line 5W50 is better.

As to why a 0W40 or a 5W50? Back in the mid 2010s, when the LT4 and LT5 were in development, to investigate ways to mitigate high wear rates that occur during cold starts, GM did exhaustive testing on how quickly the engine builds pressure in bearings during cold starts. GM developed instrumentation that allowed it to measure the time it took to reach optimal oil pressure in bearings. On a cold start, a 0W reached bearings quicker than a 5W. Now, when GM and other car companies started using 5W30s, technology had not advanced enough to make a 0W30, much less a 0W40. But by the 2010s, 0W40 engine oils were available, and starting in 2019, GM required them for Small Block V8s in Corvettes. Starting in 2023, the Gemini twins require a 5W50.

What do I use in my cars and trucks?

2016 Cadillac ATS-V Red Line 0W30
2023 Chev. Blazer RS Red Line 0W30
2024 Chev. Colorado ZR2 Red Line 0W30
2012 Corvette Z06 Red Line 0W40
2026 Corvette Z06 (after break-in) Red Line 5W50
2019 Corvette ZR1 Red Line 0W40

 

Give Hib a cigar for understanding the oil landscape over the past 30 years and the distinctions of the various grades and oil types!

I agree with the 5W-50 for the C8Z06 simply due to the different engine architecture but I am less nuanced with all my cars (and any gas powered power equipment-Lawn tractor, snowblower, generator, etc) which ALL get 0W-40 European Formula (more robust additive packages) except the LS7 with Amsoil Signature Series 0W-40, not european formula, for maximum Group IV PAO wear protection.

My cars:

American DD cars and 2 classics (1- 78 Corvette L-82 355)-0W-40-Either Mobil 1 or Castrol Edge (ONLY made in Belgium or Germany, no longer available easily).
German and Japanese Performance Cars-Mobil 1/Castrol Edge European Formula (Belgium/Germany Only). Transitioning to Pennzoil Ultra European Formula 0W-40 (made from Natural Gas, GTL)

If I was tracking any of my cars, I agree with Redline or Amsoil Signature series, 0W-40 or 5W-50. Personally, I would not use any 30W oils (0W, 5W, 10W) since the added film protection of the 40W is just free insurance on the street.

Last comment-Mobil 1 0W-40 Supercar is DexosR rated which is primarily an emissions rating with reduced (50% less ash content) than Mobil 1 0W-40 European Formula to "protect" the cats. I have never had Mobil 1 non dexosR rated 0W-40 Euro Formula oil ever foul/contaminate any cat on any car....I currently have 2 cars with 180,000 miles and 240,000 miles with OEM cats using non DexosR oils, Mobil 1/Castrol Edge 0W-40 European Formula).

 

Solid Info Hib! Good stuff!


https://americanheritageperformance.com/