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recommended oil for 75k M42?

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    recommended oil for 75k M42?

    My M42 is relatively young, 75,000 on it and it's time for an oil change. What would you guys recommend ?
    Originally posted by TSI
    ♫ Rust flecks are falling on my head...♫
    OEM+

    #2
    I have run Mobil 1 15W-50 for years and years. Filter changes every 5000 miles, oil every 10000 miles. For the most part, everything inside the engine is nice and clean at 220k miles, no burning oil and it pulled hard to redline. (I say pulled, past tense, because the timing chain decided to come loose and kill the engine back in March, but that is not oil-related)

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      #3
      10-40 is spec. I'd run that if it's healthy.
      The first car I ever rode in was an e30

      Originally posted by Cabriolet
      Wish you the best and hope you don't remember anything after 10pm.



      1992 Mauritiusblau Vert
      2011 Alpinweiss 335is coupe

      2002 540i/6 Black/Black
      2003 GSX-R 750 (RIP)

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        #4
        Castrol GTX 10w40
        or
        a Mobile 1 synthetic of similar weight
        -----Zen and the Art of e30 Maintenance - / - Zen TOC - / - Zen Summary

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          #5
          Originally posted by bmwman91
          Filter changes every 5000 miles, oil every 10000 miles.
          jesus! really?
          -----Zen and the Art of e30 Maintenance - / - Zen TOC - / - Zen Summary

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            #6
            Originally posted by bmwman91 View Post
            I have run Mobil 1 15W-50 for years and years. Filter changes every 5000 miles, oil every 10000 miles. For the most part, everything inside the engine is nice and clean at 220k miles, no burning oil and it pulled hard to redline. (I say pulled, past tense, because the timing chain decided to come loose and kill the engine back in March, but that is not oil-related)
            Thats a long interval man!

            But thanks everyone for the advice!
            Originally posted by TSI
            ♫ Rust flecks are falling on my head...♫
            OEM+

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              #7
              The whole "change your oil every 3000 miles" thing is nonsense and has been proven as such many times over the years. Even OEMs are bailing on that nonsense in their service schedules. Many modern synthetic oils say right on the bottle that they are good for 15k miles. You are just throwing money away if you change it every 3k-5k miles. Oil does not break down in that amount of time, it just gets contaminated with cylinder blow-by and whatnot. Unless your rings are completely shot to hell, you will not suffer viscous breakdown from contamination on a street engine. Modern synthetics are really good lubricants and as long as you keep a decent filter in there you will have no issues. Many people change it frequently anyway by assuming, "better safe than sorry" but it is still sort of illogical nonsense to do so.

              At this point, a lot of m42's are failing because of the overly complicated timing chain system coming apart, and a head crack between cylinder #2's exhaust valves. I have yet to see one die as a result of not changing the oil often enough or anything remotely related to that. I have owned & modded M42s for 12 years, and founded M42Club, so it isn't like I am puling this out of my ass. Your M42 will die someday from a timing chain failure or a cracked head, most likely. Well, that or a shot thrust bearing. The stock design was weak sauce in that they only put in a half-shell with a thrust surface and a lot of guys are seeing large amounts of end play in their crank. You can mitigate this by NOT pressing the clutch in when starting the car since all that does is put a bunch of force on the thrust shell when there is no oil pressure.

              Also, the spec for the M42 is 20W-50. It says so right in the owner's manual.

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                #8
                Good to know. I didn't get an owner's manual with my car.

                Hey, any chance you're still an admin on M42 club? I'd love to be more active on there but haven't been able to get my account activated.
                1991 318i SOLD
                2003 325i SOLD

                Racecars and stuff.

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                  #9
                  Originally posted by bmwman91 View Post
                  Also, the spec for the M42 is 20W-50. It says so right in the owner's manual.
                  Wow, really? I did not know that. I thought it was 10-40. Well shit, time to change my oil. No wonder I burned like 2 quarts in a couple thousand miles.
                  The first car I ever rode in was an e30

                  Originally posted by Cabriolet
                  Wish you the best and hope you don't remember anything after 10pm.



                  1992 Mauritiusblau Vert
                  2011 Alpinweiss 335is coupe

                  2002 540i/6 Black/Black
                  2003 GSX-R 750 (RIP)

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                    #10
                    Originally posted by Vivek View Post
                    No wonder I burned like 2 quarts in a couple thousand miles.
                    I was thinking that exact thing.
                    1991 318i SOLD
                    2003 325i SOLD

                    Racecars and stuff.

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                      #11
                      Originally posted by bmwman91
                      The whole "change your oil every 3000 miles" thing is nonsense and has been proven as such many times over the years. Even OEMs are bailing on that nonsense in their service schedules. Many modern synthetic oils say right on the bottle that they are good for 15k miles. You are just throwing money away if you change it every 3k-5k miles. Oil does not break down in that amount of time, it just gets contaminated with cylinder blow-by and whatnot. Unless your rings are completely shot to hell, you will not suffer viscous breakdown from contamination on a street engine. Modern synthetics are really good lubricants and as long as you keep a decent filter in there you will have no issues. Many people change it frequently anyway by assuming, "better safe than sorry" but it is still sort of illogical nonsense to do so.

                      At this point, a lot of m42's are failing because of the overly complicated timing chain system coming apart, and a head crack between cylinder #2's exhaust valves. I have yet to see one die as a result of not changing the oil often enough or anything remotely related to that. I have owned & modded M42s for 12 years, and founded M42Club, so it isn't like I am puling this out of my ass. Your M42 will die someday from a timing chain failure or a cracked head, most likely. Well, that or a shot thrust bearing. The stock design was weak sauce in that they only put in a half-shell with a thrust surface and a lot of guys are seeing large amounts of end play in their crank. You can mitigate this by NOT pressing the clutch in when starting the car since all that does is put a bunch of force on the thrust shell when there is no oil pressure.

                      Also, the spec for the M42 is 20W-50. It says so right in the owner's manual.
                      First off - thank you for your input. People like you sharing their experience and know-how are why I'm here to learn.

                      I spend a lot of time and effort trying to increase the longevity of my m42 car.. I really like the sound of a practice that mitigates known wear regarding the crank thrust bearing. I made a few attempts at starting the car w/out pressing the clutch and found it an odd practice (just wasn't used to it).

                      Also - this is the first time I've read about a preventative start-up practice regarding the thrust bearing (a subject I'm interested in).

                      Can you go into more detail on this?

                      If I understand you, my brain envisions a disengaged clutch (pedal pressed) exerting force on the crank (pulling it rearward?) - while an engaged clutch (pedal not pressed) allows the crank to spin more freely(?)

                      ..and during startup, the free(er)-spinning crank causes less wear on thrust bearing while now-circulating oil can get "in there"?
                      -----Zen and the Art of e30 Maintenance - / - Zen TOC - / - Zen Summary

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                        #12
                        I use Castrol GTX 10-30, mineral oil. And I never change my oil every 5000km, but usually do somewhere around 8000km, more less.

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                          #13
                          Originally posted by Simon S View Post
                          First off - thank you for your input. People like you sharing their experience and know-how are why I'm here to learn.

                          I spend a lot of time and effort trying to increase the longevity of my m42 car.. I really like the sound of a practice that mitigates known wear regarding the crank thrust bearing. I made a few attempts at starting the car w/out pressing the clutch and found it an odd practice (just wasn't used to it).

                          Also - this is the first time I've read about a preventative start-up practice regarding the thrust bearing (a subject I'm interested in).

                          Can you go into more detail on this?

                          If I understand you, my brain envisions a disengaged clutch (pedal pressed) exerting force on the crank (pulling it rearward?) - while an engaged clutch (pedal not pressed) allows the crank to spin more freely(?)

                          ..and during startup, the free(er)-spinning crank causes less wear on thrust bearing while now-circulating oil can get "in there"?
                          You are mostly correct, except pressing the clutch pedal in causes a forward-pushing force on the crank. But yes, pushing the clutch in when starting the engine puts hundreds of pounds of force on the half-side thrust bearing when there is no oil pressure and minimal residual oil between the crank & thrust surface. Once the car is up & running, you have the oiling system up to its minimum operating pressure and oil is pushed into where it needs to be.

                          Now, it is a relatively simple matter to fix this whole issue. To the best of my knowledge, you can actually put in a full 360 degree pair of thrust bearings without any mods to the block. Ask around on here and M42Club. A few guys have done this alreadyh. My M42 has this mod as well, but it was done by Metric Mechanic as part of a full engine build, so I am not 100% clear on which parts to use.

                          Originally posted by mr ilia View Post
                          I use Castrol GTX 10-30, mineral oil. And I never change my oil every 5000km, but usually do somewhere around 8000km, more less.
                          Nice. Even modern mineral oils are really good lubricants, compared to stuff 20 years ago. You are probably saving the most on oil out of any of us...it costs me like $47 for 5qts of synthetic!

                          Just as an aside:
                          Never, EVER use synthetic oil to break in an engine. The rings will never seat to the cylinder walls, and you will have poopy compression and burn oil forever. Use cheap mineral oil with a label that says it includes detergents. And always get the cylinder bores re-honed when replacing piston rings so that they can wear-in together. I only mention this because I read about a few M20 guys assuming that synthetic oil was "better" in all aspects, and used it for break-in with bad results.

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                            #14
                            I heard that in the german 318is E30 manual by BMW, BMW says 10w40 is the oil for the M42B18.
                            I think it always depends where in the world you live, what oil fits best for you.

                            If you live in a warm part of the united states like california or something similar, I would use a thicker oil like 10w50 or so.
                            For example I only drive my M42 in the summer, here in Germany.
                            It is like 18°C average on day or so.
                            I used 5w40 before I did rebuild my engine, and also now, its fine.

                            I heard people saying they use 0w40 for their M42, or others are using 10w60...
                            Take what you think suits best for your driving style and everything...

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                              #15
                              synthetic 10w40 all day brehh. I prefer Castrol.

                              1991 BMW 318i (Old Shell RIP, Now Being Re-shelled & Reborn)
                              1983 Peugeot 505 STI
                              1992 Volvo 240 Wagon
                              2009 Toyota 4Runner SR5 Sport 4WD

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