M42 Just Rebuilt: Oil Pressure question

[Gerta318is]

Ok, so I just fully rebuilt an M42 engine for a daily driver - both top and bottom ends went to the machine shop, new gaskets, timing components, oil pressure valve, cooling, etc ... Car currently has about 12 miles on it since the rebuild. Engine has full fluids (i.e. all new fluids - oil is dino Castrol GTX 20w / 50).

Now my questions - On start up I get the standard all lights on the cluster. The issue is the oil light stays on for a minute or two after start up. Is this normal after a rebuild? Does this go away after fully breaking in the engine (~500 - 1200 miles?). My thought is that this might be related to everything not being seated, but my OCD and paranoia won't let it go.

Any thoughts or worthwhile contributions here appreciated.

[Darky]

Did you change the oil pump or oil pressure release valve?

[Gerta318is]

No to the Oil pump as it was inspected by the machinist and noted as a good reusable piece.  The oil bypass was updated to the newer plastic part and also done at the machine shop complete with new circlip.

[Darky]

What is your climate like? Oil isn't too thick and has too warm up to become viscous?
Oil pressure relief valve can also get stuck open.

I firmly believe that the 318is should of got a oil pressure gauge not economy.

[Warsteiner]

I too question your climate and your oil choice..........

Cheers,
~Ralph

[colin86325]

I hope they didn't forget to install the oil squirters.

[Gerta318is]

Guys - I have run 20w/50 in the previous engine in both cold/hot weather and it runs fine.  It was the oil wt recommended in the owners manual.  While I know Seattle has had some colder weather ... it certainly never caused this type of oil issue being fairly temperate.

Darky - I'm thinking that might be the case as I included an engine break in additive that was quite thicker.  Do you think that could have something to do with the start up issue. 

Colin - no, I installed the oil squirters ...

[Darky]

Additive?
In oil?

[Slowered318]

I used and recommend Castrol 30 Weight Non-Detergent for the break in period. I didn't encounter oil pressure problems but I did have to replace the valve guides, seals and tappets shortly after the rebuild.. Maybe some gunk or sand was stuck inside the engine? If nothing was left out and your cam timing is dialed in correctly then you really shouldn't need to worry, It will likely take some use to get all the air and assembly lube out out of the system.

[Warsteiner]

Hey Gerta318is....Let's see if we can help you figure out your cluster light issue.

If you rebuilt the entire bottom end with new pistons and rings then you need to seat the rings properly. Using a 20/50 is like molasses unlike a well refined maple syrup and will hinder the seating of the rings as well. Now...if you didn't touch the bottom end then I'll say that the additive is your culprit because you say that you run 20/50 in both cold/hot weather.

Nowhere in the owner's manual could I find where it states to use 20/50 as oil of choice, in fact it does state to consider "special oils" which is definitively marked on the chart as 10/30 or 10/40 or 15/40. These oils range in temperature from -30*C/-22*F to 30*C/86*F. Check the outlined section. These special engine oils are individually approved by BMW as "low friction lubricants". It also states, in bold letters, BMW engines are designed to require no additives to their engines if one of today's highly advanced brand-name lubricating oils is used. Using additives could cause engine damage. Now.....we all know that was written soooo long ago!

My guess is that your oil/additive mix is too thick and and its taking that minute or two for it to start to thin out and then your oil pressure comes up. On a new engine, not having lubrication on start up is where the most damage is done by far. I would immediately change your oil, scrap adding the additive and break it in for 1,000 miles and then change your oil again and maybe use the 20/50 without the additive.

I'm guessing that should take care of your cheapest route into figuring out your cluster light issue. IF that doesn't solve it then you may need to revisit your oil pump or check valve set up.

Now for a fun fact..... The volume between the 2 marks on the dipstick equates to approx 1liter or 1.1 US quarts.

HTH,
Cheers,
~Ralph

[colin86325]

Another (small) possibility is that you have a flakey pressure sender.  You could try to verify pressure with a mechanical gauge.

[Gerta318is]

Ralph - Thanks.  I used the chart as the guide as well and put the oil in that was recommended for the temperature ranges I most commonly encounter.  I think I will visit the local parts store and grab some 15-50.  Do you think that will still be too heavy of an oil?  After all, the simplest solution is often the right one ...

BTW, thank you for the tip on the dipstick - on a similar note this dipstick can consume an additional 1.1 quarts of beer no problem.  Just a tip in case you are ever buyin' ....

Cheers,

Kevin

[Warsteiner]

Hahaha....I think a 15/50 should work fine. I run 15/40 in my M42 stroker and 20/50 in my track E30M3 2.5L which sees sustained higher temps from being on track.
We still don't know your climate because you've never told us where you live. Maybe some others could give some input as to what oil they have had good luck with after we establish your whereabouts. LOL... And then we can have some beer too....

Cheers,
~Ralph

[Gerta318is]

Ralph -

Seattle ... moderate temps currently in the low 50's.  I'll see what I can find at O'Reilly's.

Honestly, I've run 20/50 since I owned the car (2009) and not had a start up issue.  I bet the low pressure is from the additive.  Can I ask you question about engine breakin?  I've heard various things about running the engine 500-1200 miles under different load but no more than 4k rpm using dino oil.  Recommendations?

[Warsteiner]

I agree and also think its your additive.

Those rec's are ancient. With the way that oils are made these days you can use synthetic on a fresh build right away. I would still suggest changing the oil at about 1,000 but that too can be ancient. On a fresh build you may have some wear and metal will end up in the oil hence the oil change at 1K. But look at all the new vehicles that are on the market and they don't get an oil change for 11,000 miles! Times have changed....I sent oil in to Blackstone Labs and they said the oil was fine, you can go to 7,500 safely before the next oil change. Now again, that could be depending on what oil company you use.

As far as the rpm's I would vary your speed. No highway driving at same speed and load.

I would do what you normally do for intervals after the 1,000.

Cheers,
~Ralph