I did not receive your previous email. However I read this one loud and clear. I dont like the sound of the wrist pin/piston slap diagnosis as this is a mechanical condition that cannot be corrected by cleaning. However this may not be the case at all. And it may not be a serious sludging issue either. It could be that the the number 7 cylinder has coked up rings and that number 7 is not in sink with the other 7 cylinders with respect to compression due to an under performing ring pack to cylinder wall interaction. Was there any indication from your mechanic that cylinder 7 was lower than the other 7, with respect to compression? If you have a cylinder that is underperforming and for a lack of a better word dragging, you would expect to experience some fairly significant sounds and vibration which certainly needs to be corrected.
Where Auto-Rx can certainly assist is in the area of dissolving coked deposits that literally weld the upper and intermediate compression rings together and prevent their functionality. A dirty valve train, or sticky lifter can also cause for similar sounds. A bad coil, wire , or spark plug can also trigger this rapping type sound especially during operation when the motor is operated right after a cold start especially, when the fuel air mixture is rich. So these are some other areas to look at. But make no mistake, if your problems are either coked up deposits at the ring packs or valve train deposits, Auto-Rx can definitely help you out.
Auto-Rx works relatively fast in dissolving piston ring deposits. Normally, the expected results occur in the first 500 to 1000 miles, after Auto-Rx is installed. And yes, I would recommend that it be run with conventional oil. There is a great source of heat and pressure in the combustion area of the motor which makes Auto-Rx work faster. With respect to gummed up valve guides, lifters, and other top end parts the cleaning process takes longer.
Your driving habits which are very short trips, based on your email, are a contributing factor to sludging. Driving 2 miles per day to school every day of the work week is considered to be severe driving. This is because your engine never makes it up to full operating temperature. Which means that you are running a rich fuel air mixture almost constantly. Also this means that you accumulate a lot of moisture in the oiling system, because the engine never gets hot enough to boil off the moisture. So what is likely happening is you are accumulating a lot of moisture in the oil and a lot of unburned fuel in the oil. This is the perfect catalyst for sludge formation.
First I would take a look matching your oil choice to your driving habits. You receive no benefits from expensive synthetic oils. I am a big fan of Royal Purple, but only in high performance application. I am a fan of full synthetic oil but only when high engine heat is present or severe cold weather starts. For the type of driving that you are doing, you are not taking any advantage of what these high priced oils have to offer. You would likely be better of just running conventional oil and doing 3000 mile oil change intervals. With your driving habits, water or moisture is going to accumulate and fuel dilution is likely going to become an issue, regardless of oil choice at the 3000 mile mark.
My recommendation to you is as follows: Change to dino or conventional oil with a fresh filter and add Auto-Rx at a dose of 2 fluid ounces per quart of motor oil sump capacity. With the money saved with running dino oil and Auto-Rx make time to run some highway miles at full operating temperature over the course of the 3000 mile oil change interval. If you can see through the oil fill cap that you had a lot of sludging change out your oil filter at the 1500 mile mark. If not dont worry about it.
After you have completed the 3000 miles, drain the dino oil and refill with dino, a fresh filter and plan to run 3000 miles as the rinsing phase. At this point you should have cleaned up your ring packs and valve train deposits to a great degree. I would expect a significant reduction in internal motor noise at this point. In severe cases a second application is required. Remember that ARX can only help in the area of cleaning to restore oil flow to frictional parts. It will also provide for additional lubricity added to the host oil.
I hope this information is helpful to you. Please email back any questions you may have.
