There are many posts relating to AFM/DOD lifter failure. Also several posts on the improvements made to AFM/DOD over time - (thank you Monstar). I am interested in AFM/DOD, not so much from a performance point of view but really to understand any potential reliability issues which are likely to arise from the system. My unmodified 2006 VZ Thunder auto has an L76 with AFM/DOD hardware that is not activated. From what I have gleaned the hardware consists largely of: softer profile cam (than non AFM/DOD, special valley plate containing solenoids (VLOM), two part lifters on 4 cylinders. On my auto transmission L76 motor (and I understand on L76 and L77 manual transmission models) the AFM/DOD is disabled by the factory settings to the ECU software. In essence the solenoids in the valley plate/VLOM do not actuate. They are in a permanently closed position and hence oil under pressure is not diverted to the two part lifters. The lifter pins are therefore permanently in the default locked position and to all intents and purposes operate as a "normal lifter". It is widely reported that AFM/DOD lifters in early L76/L77 motors have issues with sticking. In other words the main lifter spring (not the latch pins spring) will be stuck in the compressed position. The effect is that the lifter and push rod assembly are in a shortened state and float between the camshaft lobe and the valve rocker. A ticking or clattering sound results from the lifter and push rod assembly being bounced off the rotating camshaft lobe. Damage to camshaft and lifter will likely occur if the problem is not addressed. As a sidebar, my L76 motor has AFM/DOD disabled and since the lifters are not subject to opening and closing I assume that they would not be subject to "sticking". They would not need to be replaced or upgraded - bearing in mind that I am referring to a stock motor with no performance mod's. Hence any ticking noises coming from any (L76/L77) deactivated AFM/DOD motor is unlikely to be due to faulty lifters. Would anyone like to comment on this? Returning to the matter of sticking lifters, there is a very informative AC Delco u-tube clip (Oct 2018) explaining the operation of AFM/DOD lifters. It explains that lifter failure is almost always a symptom and not the cause of engine damage. It can be caused by a mistimed switching event brought about by low oil pressure VLOM issues etc. etc. That seems to support other posts which report persisting problems despite replacing damaged lifters. Watch the video clip for details. I have seen another u-tube clip (don't recall title or date) which suggests that the lifter bores are extremely tolerance critical. The bores should be checked before replacing lifters. As per para' 1, Monstar notes that AFM/DOD systems have been improved over time. If I am reading his posts correctly it appears that by VF series 1, L77 motors will have a set up as good as it gets. They incorporate Delphi II lifters and several other mod's to increase efficiency and reliability. However there have been several posting about high oil consumption on some engines. Low km's units and apparently in good order where high oil consumption would not be expected. I am unsure whether that is only on AFM/DOD active motors or if it also applies to de-activated systems? It seems that high oil consumption is associated with AFM/DOD enabled motors. I read on another forum/post (don't recall title or date) that high oil consumption on AFM/DOD active engines is a direct result of AFM/DOD. It appears that on extended low throttle/light load freeway cruising (when 4 cylinders are de-activated) the de-activated cylinders are subject to excessive oil build up (and/or petrol?) which burns when the cylinders are put under load and the cylinders are re-activated. Over time/mileage the piston rings "gum up" resulting in high oil consumption. I would appreciate any comments on the above; particularly in relation to high oil consumption issues. Any comments at all would be useful, but the following info might help to shed some light on the issue(s):- Engine: e.g. L76/L77 Mod's or standard Model year: Total km's Oil consumption Auto or manual DOD present or not DOD enabled or disabled If you've read the post to this point you must be keen! Hope some useful information comes back.