What a Dipstick! 2 oily matters

[Jamie]

CDTi owners.... have you noticed that after your engine has cooled the dipstick registers no oil at the first check? I can tell you....this got my attention the other day! on the second dip it registered maximum. odd....but I will try to explain.

when the engine is running the oil level in the sump drops as the oil is circulated, then when you switch off the level in the sump returns....except to the tube for the dipstick....it seems that the tube is airtight and gets airlocked preventing the oil from regitering on the dipstick! when you pull out the dipper, it releases the air and allows the oil into the tube.


Secondly....Oil choice....I am currently running semi synthetic oil...but having checked two oil application charts I notice although the BMW 2L diesel uses 10/40 the MG 75 20L diesel recomended grade is 0/40 or 5/30....now is it just me or does that seem an incredibly light oil for a turbo Diesel?!! any comments?

Cheers

jamie

[M47Rman]

CDTi owners.... have you noticed that after your engine has cooled the dipstick registers no oil at the first check? I can tell you....this got my attention the other day! on the second dip it registered maximum. odd....but I will try to explain.

when the engine is running the oil level in the sump drops as the oil is circulated, then when you switch off the level in the sump returns....except to the tube for the dipstick....it seems that the tube is airtight and gets airlocked preventing the oil from regitering on the dipstick! when you pull out the dipper, it releases the air and allows the oil into the tube.


Secondly....Oil choice....I am currently running semi synthetic oil...but having checked two oil application charts I notice although the BMW 2L diesel uses 10/40 the MG 75 20L diesel recomended grade is 0/40 or 5/30....now is it just me or does that seem an incredibly light oil for a turbo Diesel?!! any comments?

Cheers

jamie

Hi Jamie
with regards to the oil level issue, you are right as to why the level does not register on the stick after the engine has been running. The reason for this is, as you say, that the tube is sealed, but also because the tube goes down into the bottom of the sump, well below the surface of the oil. The reason for this was that originally the plan in service was to use a suction machine to drain the oil, via the dipstick tube, rather than having to remove the sump plug. In fact BMW did not want to have a sump plug at all. However Rover did not think that this was acceptable in the marketplace (especially for the likes of us) and as Rover had design responsibility for the sump on M47R, we won that one!

With regard to the oil specification, I am not sure where you got the info for the BMW diesel engine. When I was working with BMW, the factory fill oil for ALL Steyr produced diesel engines was Wintershall 5W30, and BMW insisted that we use a similar type of oil. We were allowed to top up between services with Texaco Havoline 10W40, but all services were conducted with a 5W30 oil, typically Mobil 1. In fact, during all high speed testing, we had no choice but to use Mobil 1 5W30. If you can afford it, I would go for that.
I can assure you, having stripped a number of 100,000 mile and 160,000 mile durability engines, and numerous 28,000 high speed durability engines in the past, a 5W30 oil (like Mobil 1) has NO detrimental effect at all on the engine durability.
Hope this helps
Andy

[Jamie]

Hi Jamie
with regards to the oil level issue, you are right as to why the level does not register on the stick after the engine has been running. The reason for this is, as you say, that the tube is sealed, but also because the tube goes down into the bottom of the sump, well below the surface of the oil. The reason for this was that originally the plan in service was to use a suction machine to drain the oil, via the dipstick tube, rather than having to remove the sump plug. In fact BMW did not want to have a sump plug at all. However Rover did not think that this was acceptable in the marketplace (especially for the likes of us) and as Rover had design responsibility for the sump on M47R, we won that one!

With regard to the oil specification, I am not sure where you got the info for the BMW diesel engine. When I was working with BMW, the factory fill oil for ALL Steyr produced diesel engines was Wintershall 5W30, and BMW insisted that we use a similar type of oil. We were allowed to top up between services with Texaco Havoline 10W40, but all services were conducted with a 5W30 oil, typically Mobil 1. In fact, during all high speed testing, we had no choice but to use Mobil 1 5W30. If you can afford it, I would go for that.
I can assure you, having stripped a number of 100,000 mile and 160,000 mile durability engines, and numerous 28,000 high speed durability engines in the past, a 5W30 oil (like Mobil 1) has NO detrimental effect at all on the engine durability.
Hope this helps
Andy


That helps a lot Andy Thanks..... the oil grades came from a slightly older Castrol oil application chart (2001) and a Comma oil lubrication guide.....both listed 10/40 for the BM, but of course I am happy to take your advice. 5/30 it is then....changing the oil this weekend on the ZT-T..... I had bought both 10/40 semi synth Diesel and 5/30 semi syth oil for petrol or diesel.

Cheers

Jamie

[M47Rman]

That helps a lot Andy Thanks..... the oil grades came from a slightly older Castrol oil application chart (2001) and a Comma oil lubrication guide.....both listed 10/40 for the BM, but of course I am happy to take your advice. 5/30 it is then....changing the oil this weekend on the ZT-T..... I had bought both 10/40 semi synth Diesel and 5/30 semi syth oil for petrol or diesel.

Cheers

Jamie

Glad to be of help Jamie. Your engine would run happily on either of the oils, but this time of year, as the temperature drops, a 5W30 oil will help reduce internal friction during cold starts, and you may find it even helps your fuel cons a little bit. I have had a lot of success in the past using Millers semi synthetic oil (although not in the M47R engine), and have routinely had an improvment of 1 to 2 mpg when switching from a standard mineral oil to millers semi synthetic.
Having said all of that, if of course your engine has done 200,000 miles, with the expected amount of bore/piston wear at that mileage you may find that the 10W40 might be more appropriate!!
Hope I have not confused matters now
Andy

[Jamie]

Glad to be of help Jamie. Your engine would run happily on either of the oils, but this time of year, as the temperature drops, a 5W30 oil will help reduce internal friction during cold starts, and you may find it even helps your fuel cons a little bit. I have had a lot of success in the past using Millers semi synthetic oil (although not in the M47R engine), and have routinely had an improvment of 1 to 2 mpg when switching from a standard mineral oil to millers semi synthetic.
Having said all of that, if of course your engine has done 200,000 miles, with the expected amount of bore/piston wear at that mileage you may find that the 10W40 might be more appropriate!!
Hope I have not confused matters now
Andy


No confusion Andy....makes perfect sense...the ZT has only covered 29k so I will go for the 5/30.

Cheers

[baxlin]

Thanks for these explanations. I put a post on the .org one asking about this, as my 75 is my first diesel. At the time, although there were replies, for once the Q wasn't completely answered. Now it is, so thanks!!