|Topic Review (Newest First)|
|09-27-2015 05:01 AM|
|NJBourne23||This is why I run 93. I heard from a few others that it helps to prevent stretching|
|03-20-2015 10:55 AM|
Originally Posted by S.Bretz View Post
|03-18-2015 06:20 PM|
I have found the oil life monitor works pretty well in the last few resent years, but it needs a certain set of parameters to be accurate. The system relies on a good working engine with minimal blow-by. This means as the engine wears (after break-in) the oil life monitor becomes a little less accurate with each passing mile. The other, more important parameter that the system relies on it the oil LEVEL. If you have 1/2 the oil, the oil that is in the system will be going around twice as much, therefor the oil wears out twice as fast. Check the level and keep it up to the full level on the stick. Even if you think you engine doesn't use any oil, still check the level. Make it a habit to check the level the first weekend of every month and you should be ok unless you have major oil consumption issues.
I have seen vehicles come into service with misfires from low oil on the v6. The reason is that there is not enough oil in the system to provide proper hydraulic pressure to the cam actuators. The ECM expects the cams to move but they are stay locked on the parking pins. Adding oil back to the system solves it. In all the cases I have had, I have recommended an oil change because the oil level was so low that the oil left in the system was pretty much spent.
I have seen other guys in the shop get tickets (repair orders) on vehicles with complaints of misfires and also an oil change. The tech brings the car in and does the oil change first and then gets a "cannot duplicate" on the misfire concern. I would ask if they check the oil level first and usually the reply was "no."
|03-18-2015 12:09 PM|
The DEXOS approved oil used by the dealer is a synthetic blend. Fine for the average push-rod engine but these high revving (7k redline), high compression (11.5:1) double overhead cam DI engines need a good full syn to protect properly. Far more parts and closer tolerances with 3 timing chains and the related tensioners and guides. This is all marketing with the deal between GM and M1......just look at the V8 LS3/L99, it states M1 full syn only in the past years, but it is an engine rarely turning over 5-5500 RPM and far fewer moving parts with very few as wear prone as overhead cam engines, and then it is 10.4-10.7:1...when the V6 needs that extra protection far more than the V8.
The reason 87 octane (makes more power and gets better MPG with 91-93) is recommended and the cheaper oil is all marketing. The buyer of a lower cost V6 marketing has determined is attracted to cheaper fuel, lower cost oil changes (aside from the free changes) etc. (all around lower cost of ownership appeals to the economy minded). It has nothing to do with what is "best" for the engine or the vehicle. That only comes into play when the vehicles reach commercial needs where longevity is critical to the prospective buyer. All modern cars and light trucks have the ability with the superior quality control and materials to last 200-300-400k miles if properly cared for, but this runs contrary to selling new cars & trucks. Just as people drive to 8-10k miles on that first factory oil fill.....very bad for the engines life, but the owners manual states they should. Planned obsolescence.
I agree w/you on M1 as well. Years ago it was among the best, but then they removed most of the zinc/phosphorus from the formula (anti scuff/wear additive) due to GM's not wanting it so a Pennzoil, Valvoline, or Quaker State is far better now. We used M1 years ago in our Alky fueled dragsters and on average we put 300-350 rounds a year on each, and the protection was great. We have since moved to Valvoline full syn or preferably Amsoil or similar after they changed the formulation of M1. M1 is still fine for average daily drivers....but for the $ I go for one of the others.
As far as thinner weights, less shear equals less resistance and better MPG to meet the CAFE standards. So your on the right track there as well. I don't think there is risk of using it though as it still provides a good barrier. We use different oils for different applications in the race engines. The Top Dragster, Super Comp, etc. we run a heavier weight as we build them a little "looser" than a street engine as we freshen every season end (replace springs and lifters 1/2 season to avoid unexpected failures) to make more power. But on the heads up engines (quickest to the finish line) we run as thin as will protect for even more power knowing we will tear them down every few races and replace bearings as needed. Same with oil pressure. We run lower pressure on heads up engines for less parasitic power loss. What you DON'T want to do with todays close tolerance street engines is to run a heavy oil like a 15w50 that was fine in the past with traditional old SBC/BBC engines. That can actually cause less protection due to flow, etc.
DEXO's is far better than the conventional's of the past, but these new smaller displacement higher revving higher compression engines need a lower weight oil so a 5w20 or even a 0w20 is fine as long as it is a good FULL synthetic.
Hope this helps!
|03-17-2015 07:59 PM|
that's good reading, and here I am letting the dealership put the standard Dexos oil in my car thinking it's good oil... what exactly is the fault in dexos oil? I thought it was a semi-synthetic oil?.. I'm reading that manufacturers are specifying thinner oil to maximize efficiency, I hope they are not sacrificing durability for that silly reason.
I think I ought to go synthetic from now on.. also in my experience I've never been impressed with M1 oil either, it seems to wear out in 3,000 miles just like conventional.
|03-16-2015 11:43 AM|
Originally Posted by CyberPunk223 View Post
Probably wont find many members that tear these down as often as we do, and we see these failures all the time. Most never even check their own oil between changes and rely on the "dealer" who does the changes. Run these more than 2 qts low and you will sustain damage whether you notice it or not, and it is crazy (No, GM does NO break-in on any engine other than the C7 corvette gets a slight run-in...but not enough to accomplish any break-in) that owners actually leave that debris fill initial oil fill in for 5-10k miles.
As a vehicle owner today, trusting in what the owners manual or deal tells you will rarely result in taking proper care of a new vehicle...you must get some education and somehow sift through all the BS marketing (and on most forums, the BS posted by all the key-board experts that make assumptions).
Back in the "old days" (Started with GM in 1974 as a Factory trained tech) all came pre-filled with break-in oil that provided enough protection for the bearings and journals if driven very easy (where the current owner manual break-in came from) but still allowed the rings to penetrate the lubrication barrier to allow abrading of the rings to the cylinder wall for proper seating. It was critical to get that oil out in 500-1000 miles max, and then with standard oil fill you could drive more aggressively. Now, there is still the assy debris and break-in metal filings, etc. circulating, and the oil filter can only trap so much, that leaving it in is horrible for the life of the engine. I still suspect this is "planned wear" as these engines will go 300-500k miles if cared for now and auto maker want to sell new cars, but that is an opinion only...I have no proof other than we see all the wear when tearing these down (same as all the pictures others share).
Cyberpunk understands it, like many other true mechanics, but people need to understand, marketing and sales are the main focus of any auto maker....NOT educating you on the best way to make your investment last. Just as they "reccomend" DEXOS blend oil, when that is a sure way to shorter engine life...after the intial break-in and drain, ALWAYS use a good full syn oil (M1 is near the bottom of that list..Valvoline, Pennzoil, etc. far better full syn, premium like Amsoil, etc. even better).
The problem with the consumption issues is these engines come pre-filled with the same oil to run all times, so it is creating a lubrication barrier that the rings cannot easily penetrate unless loaded hard as the "accurate" GM break-in instructions above provide (written by actual hands on engineers and the owners manual by PR, Legal, Marketing, and management.). You only have that short window of the first few hundred miles (300-500 max on average) for the rings to abrade to the cross-hatch hone cut on the cylinder walls. Here are some illustrations to show what happens when ring seating occurs properly, and when it only accomplishes partial seating before the hard glaze sets in:
So, as the piston rings in today's DI engines are a lower tension ring set so it makes this seating even more dependent upon lubrication barrier penetration and hard even loading both during acceleration and deceleration. If you follow the owners manual you just may achieve proper ring seat, but the odds are you wont. And after this period passes, the ONLY way to seat the rings are to dissemble the engine, cut the glaze from the cylinder walls with another hone job to cut the proper cross hatch abrasive pattern, and start over (preferably with a new set of rings). Anyone that assumes break in still occurs for thousands of miles has never had a master engine builder show them all these parts first hand. So, follow the GM engineer's instructions if you want to assure all is done correctly and you avoid the oil consumption issues from day one.
Now, the engine oil the car comes with from the factory will have all sorts of debris, dirt, filings, etc. in it (cut your oil filter if a canister type...or open the pleats and examine if a drop in cartridge style (LLT/LFX) and see for yourself all the different junk in it! NEVER can this oil be left in an engine more than say 1000 miles w/out causing premature wear and shortened engine life.
Now, NOTHING else needs to be broken in easy in the drivetrain!!!! All trans gears are as perfect as they will be after the first 20-30 miles. Only the rear diff ring and pinion gears need any wear-in, and that happens also in less than 100 miles. Nothing in the torque converter (or clutch/PP-plate) U joints, etc. need any break-in aside from that first 20-30 miles. So, brakes bed in the first few stops...hard stops, do NOT leave pads clamped on hot rotor. Cool and repeat. Engine and rest just a few easy heat cycles to ensure no unusual noises that could indicate a material defect causing a mechanical failure occurring.
Anyone with more questions, just ask. With the new Company I don't get much time to visit the forums anymore, but will still share and help wade through the BS and the facts.
|03-14-2015 08:35 PM|
|83Hokie||I've me a firm believer in the every 5000 miles oil change ... easy to keep track of, under what theoem requires, and even with synthetic, relatively cheap|
|03-14-2015 06:19 PM|
Originally Posted by SC2150 View Post
I'll say 1 more thing, the oil monitors in these cars are junk,, I had 7200 miles on my oil and the oil life monitor was still saying over 20% oil life.. I looked at the oil and it was in real bad shape.. I'm just going to start changing the oil every 5,000 miles regularly, I believe they are calling for less frequent oil changes so engines so bad faster..
Alan Watt talked about this on his show back on December 28th I think, about how all these car manufactures were doing things in the factory to purposely shorten the life of cars, they've been doing this forever. He also said the latest craze of making really small turbo charged high revving motors are motors that will just burn up much faster. 60,000 miles and they will be toast. because they have to rev so high just to maintain speed. it's funny how they tote these things as improvements.
It's crazy that low oil can cause these kind of majors failures,, AND THEY DIDNT EVEN INSTALL A LOW OIL INDICATOR?? coincidence? yeah right!!.. I guess this is why they say oil level should be checked at every fill up. stuff is crazy..
|03-11-2015 04:15 PM|
To add to this thread, none of the LLT's or LFX's had low oil indicators until 2014. Most don't check oil regularly so oil starvation is quite common as these are oil eaters if driven easy during the break in period (first few hundred miles). The dealers use a DEXOS approved syn blend oil....run full syn after break-in and timing chain stretch is less of an issue. Can't list how many turned bearings I have seen, most from running low oil level not realizing it. Also, the timing chain tensioners rely on oil pressure to maintain tension so if you are low even a few qt's, a sudden stop/start/corner can cause cavitation when the pick up sucks air and that is all it takes for the tensioner to collapse (the spring back up is not strong enough to maintain) and allow the chains to jump teeth.
But as most don't change the initial oil fill until 5-10k miles, a ton of wear occurs from the debris from assembly and initial wear in (no matter what the owners manual says) and even a small amount of debris traveling through the bearings and journals starts damage that may take years to see a failure from.
Here is what GM gives us with replacement engines on proper break-in...the only thing I do different is run up to 5-6k RPM and engine brake down to really load the rings properly. After a few hundred miles if your rings have not seated, they never will as the hard glaze sets on the cylinder walls by 400-500 miles and that brief window has passed:
So, to head off the "the owners manual would not mislead us" are they lying to the owners, or lying to us the techs.......You decide.
|03-11-2015 03:03 PM|
Welcome to the blown LLT club. I'm in the same boat, stepped on the gas to merge onto the highway (only about 4500rpm, closest its been to redline since I've owned it) and after I let off I noticed a ticking sound when the car was maintaining speed. After 2-3 min it went away.
Got in the car the next day and the tick was back. Decided to drop it off at the dealer who diagnosed an Exhaust leak. Picked the car up after they 'fixed' it and the noise was worse.
Well come to find out the #4 bearing failed... not spun... failed. Took the crank with it.
still under warranty but the dealer is making a case for replacement instead of repair to GM.
BTW only at 42k miles
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