Those who've seen my posts over the years may remember that I've tried A-RX (two clean/rinse cycles) in this engine and reported no change in any performance or appearance aspect. I've also run MMO in the oil for brief periods to attempt some cosmetic cleaning. The engine runs great and has good compression but has always (in the time I've owned it) had heavy black/amber carbon/varnish deposits in the visible portions of the top end (under valve cover). Though it doesn't seem to affect any aspect of performance I have been curious whether similar deposits elsewhere in the engine might be affecting performance in unknown ways and whether it could be removed through the use of any reasonably safe cleaning product.
Following the separate thread here on a successful solvent flush,
https://bobistheoilguy.com/forums/threads/oil-consumption-cut-in-half-after-solvent-flush.82870/
and research into other similar threads over the years, I decided to try the same thing myself. The engine needed a new pan gasket, which would give me the opportunity to remove the pan after the flush to check for deposits in the lower end and any gunk left in the pan after the flush.
There is, perhaps unfortunately, not much to report. I put in a fresh batch of cheap oil and spun on a new oil filter, and added a qt of CRC engine flush to the crankcase. The directions say to idle for 5 mins then drain, much like other solvent flush products, but I attempted to increase the effects by idling 5mins every half hour or so for several hours. A couple of longer idling periods were thrown in, and in the last, just before draining, I set the engine to high-idle at 1800rpm for about ten minutes (after 10min at regular idle) before shutting down.
The "new" oil darkened slightly, to a light amber color. The pan had nothing but clean (slightly darkened) oil in it. No gunk or other foreign material was present. There was no change in any apparent aspect of engine operation. There was no visible change in the appearance of the under-valve-cover area and I noted when the pan was off that the bottom end of the engine had similar dark carbon deposits.
As far as I can tell the flush had exactly the same effect on this engine as A-RX did: none, or close enough to none to be considered inconsequential.
FYI, YMMV.
Following the separate thread here on a successful solvent flush,
https://bobistheoilguy.com/forums/threads/oil-consumption-cut-in-half-after-solvent-flush.82870/
and research into other similar threads over the years, I decided to try the same thing myself. The engine needed a new pan gasket, which would give me the opportunity to remove the pan after the flush to check for deposits in the lower end and any gunk left in the pan after the flush.
There is, perhaps unfortunately, not much to report. I put in a fresh batch of cheap oil and spun on a new oil filter, and added a qt of CRC engine flush to the crankcase. The directions say to idle for 5 mins then drain, much like other solvent flush products, but I attempted to increase the effects by idling 5mins every half hour or so for several hours. A couple of longer idling periods were thrown in, and in the last, just before draining, I set the engine to high-idle at 1800rpm for about ten minutes (after 10min at regular idle) before shutting down.
The "new" oil darkened slightly, to a light amber color. The pan had nothing but clean (slightly darkened) oil in it. No gunk or other foreign material was present. There was no change in any apparent aspect of engine operation. There was no visible change in the appearance of the under-valve-cover area and I noted when the pan was off that the bottom end of the engine had similar dark carbon deposits.
As far as I can tell the flush had exactly the same effect on this engine as A-RX did: none, or close enough to none to be considered inconsequential.
FYI, YMMV.
