Can lighter than specified oil be used? BMW 323i

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I recently bought a BMW 323i and replaced all the fluids in the car. As I was going through the oil though, I decided to give it a kerosene flush and then changed the oil. This new oil I ran was Napa 15w-40 Diesel oil and I put in a whole bottle of Auto-RX and ran it for 3000 miles. At the end of this interval, I did another kerosene flush (mixture - 30 minutes at idle). Both times the oil came out extremely dark brown and vaguely reddish. This time, however, I needed to do the rinse cycle. I found a deal at Advanced Auto Parts for 5 quarts and an oil filter for $20 + one quart. I decided to buy Castrol GTX 5w-20 oil to give it a shot mpg wise. I am extremely light in my driving style and you will usually see me driving at or slightly below the speed limit in the right lane so I tend to think that I am very easy on the oil. I always accelerate slowly and shift early so the engine rarely goes over 2400 rpm. My question is whether anyone has ever run 20 weight oil specified for a car whose manufacturer specifies 30 weight oil? Ford retroactively specified 20 weight for all cars post 1992 and I think this may have implications beyond marketing and getting cars to self destruct so their owners buy new ones. If Ford cars 1992+ have greater bearing clearances than my 3/2000 BMW M52TUB25 then shouldn't 20 weight oil fit the bill perfectly for my car? Just food for thought. I am interested in what people have to say about this. Let me know if I am not clear about something.
 

djlinux64

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It has 110,000 miles and has used BMW oil for its whole life. Engine seems to be in good condition with minor varnish that I am slowly dealing with by running short OCI on Castrol dino. Old OCI were 15,000 miles though It has absolutely no discernible oil burning. The level never budges by even a millimeter.
 
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I really don't want to get into explaining much, as I am hungry and need to eat. Stick to 30W to 40W based oils. I wouldn't do 20W. My BMW has never seen 20W oils and it never will.
 
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I am running M1 0W20 in 2000 E430, the recommended oil is M1 0W40. The engine seems to like thinner oil, better MPG and much quieter. No oil consumption with either 0W40 or 0W20. Before this M1 0W20, it had PP 5W20 with same results: better MPG and quiet. The oil change will use Synpower 5W20.
 

djlinux64

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I wish I had the patience to do a Blackstone analysis. HTSS_TR have you ever considered looking at wear metals from your E430 especially after driving it for a while in SoCal?
 
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I definately wouldn't do a 15K OCI interval in a BMW, to me that was a marketing ploy to give the appearance of less maintenance...many of have seen what a 15-20K OCI looks like in these cars, sludge-time...
 

djlinux64

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 Originally Posted By: Smokescreen
I definately wouldn't do a 15K OCI interval in a BMW, to me that was a marketing ploy to give the appearance of less maintenance...many of have seen what a 15-20K OCI looks like in these cars, sludge-time...
Agreed.
 
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http://www.bobistheoilguy.com/aehaas/ Dr. Haas has a stable of racing cars etc. and will use a 20 weight when manual is calling for a 20w50. After I read some of his stuff, I cautiously used a mixture of 50:50 5w20 conventional with 5w30 synthetic in my Mitsubishi 1.5l 12v NA engine, and in my Subaru 2.5 NA flat four. Both engines ran well, but I only use this mix in the winter. In the summer I prefer something like 5w30 conv/synthetic blend, or even 5w30conv/10w30synthetic blend, depending on whether I am planning city use (blend 1) vs long highway use (blend 2). Just read Dr. Haas articles on oil for a full explanation. My own inclination would be try one part 5w20 Motorcraft semi syn with 2 parts 5w30 full syn. (a 5w27) I tend to like to use my oil pan heater/block heater even in slightly chilly weather, because I run mainly short trips, and if you put your heaters on a timer, your mileage is better, wear on the engine is less, and your electric bill is not affected much.
 
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FZ1

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Don't do it,man. Just run the spec'd weight. Go get some PP at Walmart. 5 quart jug,$20. 7500 oci.
 
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Stick with the spec (ACEA A3). Flush with some GTX 10W40, another 15W40 or something from Walmart. Running an even thinner oil will make the VANOS problem you probably have (if you have an M52, M52TU or M54) worse. I also question your jump straight to a kerosene flush including between the ARX clean and rinse phases, but that's another story. Remember that the oil does more than just cams and rings (tensioners, continuously variable cam timing controls, ...)
 
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 Originally Posted By: djlinux64
Ford retroactively specified 20 weight for all cars post 1992 and I think this may have implications beyond marketing and getting cars to self destruct so their owners buy new ones.
Ford did not spec 20 wt for all engines to get them to self-destruct. The 4.0 SOHC V6 used in Mustangs, Explorers, and Rangers is still speced for 5w-30. Ford did that for a reason. Perhaps to prevent the engine from self-destructing? It really irks me when people say manufacturers want their products to fail. The manufacturers know that they will sell more products in the long run if their products last a really really long time. For example: I am by no means a Toyota fan, but like it or not, they have a reputation for making cars that last a really long time. And they're, what, the largest or second largest automaker now? Coincidence? Nope. So no, Ford did not spec all engines to run 5w-20, and they certainly didn't do it to make their engines break. Rant over.
 
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PP 5w-30 seem to work in the Audis, turbo and non turbo. http://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=1523518&gonew=1#UNREAD http://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=1523520&gonew=1#UNREAD In the BMW, it all depends on the oil temp. +/- 10 degrees difference can make a 30 into a 40 or the other way aroud. http://www.widman.biz/Seleccion/Viscosidad/Conversiones/Graph/graph.html At the reported +140c operating temps, the BMW oil is thinned to a 20 weight, but wear remains fine. So, someone driving lightly and short distances can use a thinner oil VERY effectively.
 
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The E46 323i initially specified BMW LL-98 oils which were 5W-40 viscosity. In 2001 the specification was changed to BMW LL-01 which was a 5W-30 viscosity. BMW has specified this viscosity across their product range ever since with a few exceptions. Your admitted light duty cycles and ease of operation may reduce the need for BMW's specific oil standard (currently LL-04). However, I personally would stick with a 5W-30 viscosity lube and exercise modest drain intervals. I own a 1999 323i with the same engine as yours and it has served me very well for past 10 years. It isn't too picky about what you run and I have never noticed a difference in engine noise or sluggishness with any oil I've used. On a maintenance note, there are two O-rings on the oil filter cap that you should change on occasion. The O-rings do not come with the filter but they are specified to be changed with each oil drain. They are at the end of the plastic rod attached to the cap. A car of this age may have never had them changed and they will get hard and fail. I see no practical reason to use a Xw-20 viscosity oil that doesn't meet any euro specification when there are applicable alternatives available.
 
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