"Using Diesel-spec oil (API Service Cx) isn't a problem - provided it has a gasoline spec (API Service Sx) as well. There are a couple of additives required in one that aren't required in the other - this is why the new API "Energy Saving" spec (API Service SM) has no equivalent Diesel spec. For instance, it doesn't have enough acid neutralisers in it (Diesels will rapidly form sulphuric acid in the engine oil. New "low-sulphur" Diesel fuels mitigate this somewhat, but it's still present. Diesels - and flat-tappet gasoline engines - also require anti-scuff additives. These are typically organometallic compounds that will rapidly poison a catalyst bed.)
This is why I've been telling owners of the 242ci engine to avoid oils with the API Energy Saving "sunburst" on the front of the bottle - and to flip the bottle over and check the back anyway. Don't use API Service SM in flat-tappet engines. Camshaft failure will result eventually. Not in a single oil change, but consistent use will make failure a certainty.
Shell Rotella T is specified, I believe, API SL/CJ-4, which is acceptable for use with flat tappets. Synthetics - particularly performance synthetics - may have SM-spec oil useful with flat tappet engines, but check manufacturer literature (some new anti-scuff additives are probably being developed, but they're not mainstream yet.)
This is akin to the failures that result from using NGLI Service GL-5 gear oil in manual transmissions that have bronze synchroniser rings - the sulphur added is antagonistic to yellow (copper and copper-based alloy) metals, and it will dissolve the bronze (given time.) This results in losing synchroniser rings and bushings in the case. Some "performance synthetic" gear oils (Amsoil and Redline in particular) carry a GL-5 spec without using added sulphur as an Extreme Pressure (EP) lubricant, and therefore will serve with yellow metal. Manufacturer literature will specifically state such service - if you're not sure, put GL-3 in your AX-4/5/15 instead. NLGI Service GL-5 is still available in most places.
Of course, if you're using synthetic in an engine that tolerates it will (the seals don't get crud flushed off of them and they start to leak, or excessive blowby results. These are wear/service factore, and have nothing to do with the oil!) a change interval of 15,000-18,000 miles is perfectly acceptable. F'r instance, my wife's car (2005 Suzuki Verona) saw me switching from dino oil for break-in, at 30,000 miles, to a full synthetic oil - and going from a 3,000-mile change interval to a 15,000-mile change interval. This justifies spending the extra for synthetic - it costs about twice as much, but will run five times as long.
Use a quality filter - if I can't find Baldwin, I'll use Wix. I don't consider anything else acceptable. A "house brand" oil filter is acceptable - if it's made by Baldwin or Wix. Ask. If they can't tell you (or the answer is something other than Baldwin or Wix,) pay the extra buck or two for a real Baldwin or Wix filter - it's worth it. If you have to stock up and order them by the case (typically twelve pieces,) go ahead and do so.
Ideally, you'll want to switch an engine to full synthetic at 25,000-50,000 miles, for minimal trouble. This is long enough to allow for full run-in and "part lapping,) but not so long that you'll flush crud off the back of your seals and find leaks you'd have eventually found anyhow. If you want to switch well after that, you'll want to flush your engine - this can be done (in service) by substituting one quart of oil with one quart of automatic transmission fluid (preferably Type F if you can find it - it's higher in detergent) for a couple of changes before the switch. This usually gets the crud out that has been building up, and will allow you to see if any seals want changing before the actual switch. (It's an old mechanic's trick. The base oil for transmission fluid and engine oil is the same, it's just that the transmission fluid is a straight 10-vis oil. The detergent content is much higher in ATF, and highest in Type F. I've also used it for an ersatz hand cleaner - get the crud off with Type F, wash the Type F off with regular hand soap. Run a normal 3,000-mile change interval when you do this.)
Once you switch to synthetic, you can extend your change interval significantly. Add a "bypass" oil filter (a secondary extra-fine filter that cleans the little crud out of the oil and returns it to the sump,) and you can probably extend your change intervals still farther. The base oil doesn't break down - it's the additives that eventually fail. This is why oil can be "rerefined" - crack off the additives, add a new additive package, and resell it. I wish I could still find rerefined oil...fail. This is why oil can be "rerefined" - crack off the additives, add a new additive package, and resell it. I wish I could still find rerefined oil..."
===============================================================
Only diesels and flat-tappets require "anti-scuff" compounds?
Camshaft failure will result? My uoa's don't say so.
15,000 oci's without uoa's?
No new engines should run synthetic right away?
I need to flush my engine before switching to synthetic? And use ATF of all things? Type F has the most detergents?
Can't find rerefined oil???
One of the other responses said current engine oils have less detergents than ATF's...
This was posted on an oil topic over at a Jeep forum I regular. Great forum for mechanical advice, I've given more than my fair share. Stuff I don't know I won't post. It boggles my mind on how much misinformation there is though.
I've decided to stop posting in oil related topics. Most would rather die than believe that an ATF crankcase flush doesn't do anything.
This is why I've been telling owners of the 242ci engine to avoid oils with the API Energy Saving "sunburst" on the front of the bottle - and to flip the bottle over and check the back anyway. Don't use API Service SM in flat-tappet engines. Camshaft failure will result eventually. Not in a single oil change, but consistent use will make failure a certainty.
Shell Rotella T is specified, I believe, API SL/CJ-4, which is acceptable for use with flat tappets. Synthetics - particularly performance synthetics - may have SM-spec oil useful with flat tappet engines, but check manufacturer literature (some new anti-scuff additives are probably being developed, but they're not mainstream yet.)
This is akin to the failures that result from using NGLI Service GL-5 gear oil in manual transmissions that have bronze synchroniser rings - the sulphur added is antagonistic to yellow (copper and copper-based alloy) metals, and it will dissolve the bronze (given time.) This results in losing synchroniser rings and bushings in the case. Some "performance synthetic" gear oils (Amsoil and Redline in particular) carry a GL-5 spec without using added sulphur as an Extreme Pressure (EP) lubricant, and therefore will serve with yellow metal. Manufacturer literature will specifically state such service - if you're not sure, put GL-3 in your AX-4/5/15 instead. NLGI Service GL-5 is still available in most places.
Of course, if you're using synthetic in an engine that tolerates it will (the seals don't get crud flushed off of them and they start to leak, or excessive blowby results. These are wear/service factore, and have nothing to do with the oil!) a change interval of 15,000-18,000 miles is perfectly acceptable. F'r instance, my wife's car (2005 Suzuki Verona) saw me switching from dino oil for break-in, at 30,000 miles, to a full synthetic oil - and going from a 3,000-mile change interval to a 15,000-mile change interval. This justifies spending the extra for synthetic - it costs about twice as much, but will run five times as long.
Use a quality filter - if I can't find Baldwin, I'll use Wix. I don't consider anything else acceptable. A "house brand" oil filter is acceptable - if it's made by Baldwin or Wix. Ask. If they can't tell you (or the answer is something other than Baldwin or Wix,) pay the extra buck or two for a real Baldwin or Wix filter - it's worth it. If you have to stock up and order them by the case (typically twelve pieces,) go ahead and do so.
Ideally, you'll want to switch an engine to full synthetic at 25,000-50,000 miles, for minimal trouble. This is long enough to allow for full run-in and "part lapping,) but not so long that you'll flush crud off the back of your seals and find leaks you'd have eventually found anyhow. If you want to switch well after that, you'll want to flush your engine - this can be done (in service) by substituting one quart of oil with one quart of automatic transmission fluid (preferably Type F if you can find it - it's higher in detergent) for a couple of changes before the switch. This usually gets the crud out that has been building up, and will allow you to see if any seals want changing before the actual switch. (It's an old mechanic's trick. The base oil for transmission fluid and engine oil is the same, it's just that the transmission fluid is a straight 10-vis oil. The detergent content is much higher in ATF, and highest in Type F. I've also used it for an ersatz hand cleaner - get the crud off with Type F, wash the Type F off with regular hand soap. Run a normal 3,000-mile change interval when you do this.)
Once you switch to synthetic, you can extend your change interval significantly. Add a "bypass" oil filter (a secondary extra-fine filter that cleans the little crud out of the oil and returns it to the sump,) and you can probably extend your change intervals still farther. The base oil doesn't break down - it's the additives that eventually fail. This is why oil can be "rerefined" - crack off the additives, add a new additive package, and resell it. I wish I could still find rerefined oil...fail. This is why oil can be "rerefined" - crack off the additives, add a new additive package, and resell it. I wish I could still find rerefined oil..."
===============================================================
Only diesels and flat-tappets require "anti-scuff" compounds?
Camshaft failure will result? My uoa's don't say so.
15,000 oci's without uoa's?
No new engines should run synthetic right away?
I need to flush my engine before switching to synthetic? And use ATF of all things? Type F has the most detergents?
Can't find rerefined oil???
One of the other responses said current engine oils have less detergents than ATF's...
This was posted on an oil topic over at a Jeep forum I regular. Great forum for mechanical advice, I've given more than my fair share. Stuff I don't know I won't post. It boggles my mind on how much misinformation there is though.
I've decided to stop posting in oil related topics. Most would rather die than believe that an ATF crankcase flush doesn't do anything.
