Thin oil and hydraulic lifters

pbonsalb wrote

If I was losing 20 rwhp due to valve float from collapsing lifters up top, I would put 10W60 back in rather than try a compromise oil that might lose only 10 rwhp up top.

My understanding is that a year or two ago the engineers at BMW revised the oil spec for the S65 to include any weight LL-01 rated oil such as Mobil 1 0W40, Castrol 10W60, and Castrol Edge Professional 5w30. I assume BMW would not have revised the spec to include lighter weight oils if it could result in valve float

You have a point. If there is no difference then I can dump the 10/60 and put whatever I want back in, I'm just out a 100 bucks but will know for sure. Question is, if there is a measurable difference with the 10/60, then what? Keep it or go back for start up protection? Still can't believe someone hasn't done this yet. I'd do it sooner but I want to put another 1000k miles on the pu for Blackstone.

To be clear, I'm not saying I think I lost x amount of HP. In reality, I can't put my finger on it, it just felt weaker after the swap. I'm more interested in studying the powerband and torque curve than comparing peak #'s.

Leonardo629 wrote

Doc,

I've dyno'ed my car with M1 0W40, the chart looks like any other chart from Dynojet, the engine makes power all the way to redline, flat torque curve after 2500rpm or so.

My car made 357hp/262ft-lb on a 104F day here in So. Cal.

I keep on telling myself with a tune/test pipe/lower temperature, my car could be pushing 400whp!!

This graph is definetely way too flat up top. Supposed to climb more linear

8600RPM wrote

This graph is definetely way too flat up top. Supposed to climb more linear

If you google s65 dyno results it gives you pages of images. His is definitely the flattest I saw from 7k to redline.

I concur. Either is spark plugs are bad, coils bad or he does have lifter problems. I threshing he runs 0w40.so etching isn't working on his car

Castrol 10w60 shears down to a +-40w relatively quickly and with BMW recommending 15k mile oci I can't see the lifter thing being a real consideration

It doesn't sheer to a,40. More like a 50.also never below the viscosity of 0w40.

Don't all oils shear? If so, what is 0w40 shearing to?

8600RPM wrote

That supposed document was nothing more than an error in labelling. At no time as bmw approved anything but 10w60 for use other than emergency top offs with a lower weight.

Again, you can't say any hydraulic lifter engine is the same. It's oil pressure that is key so if an engine is designed with a grade to begin with, the design would incorporate the oil pressure they targeted
We are changing oil pressure in an engine not designed for it. Whether it matters who knows

You are right. I found a second BMW document that states the only LL-01 oils for the S54, S65 and S85 are 10W60.

But I still think it is a leap to conclude the top end power flattening in one particular car is due to thin oil based on a dyno plot. You do not even know what oil the owner was running.

I also think it is a leap to conclude power is down slightly on the top end based on your butt dyno and that it is due to valve float from thin oil.

Most people switching to thinner oil say the opposite -- the car feels faster. Again, I am not sure I believe those butt dynos either. My guess is that the difference on the dyno between a 0W40 and a 10W60 is a matter of a few rwhp in favor of the 0W40, not enough for the average person to be able to feel.

I agree that this can be a theory. I just think that if there was anything to it, other car enthusiasts over the years with high rpm engines would have experienced it and in my limited searching, I found no support. But back to back dyno testing with thick and thin oil should support or disprove the theory. Go for it. I'll keep my 0W40 for now but will switch back to 10W60 if you prove it adds power.

I do plan to dyno this fall and will share my naturally aspirated 0W40 dyno. I am hoping it won't be flattening out on top, but we will see.

Lifters are driven off oil pressure not viscosity. 87psi is the high limit of the bmw spec. The 0-40 is still on the bypass at high rpm. Liquid cant be compressed therefore the valve lift is still the same. The only way the valve could compress is if the pump could not supply enough pressure to ever get on the bypass. This is not the case of the s65. My gauges have logged 90psi at 8700rpm. That is actually a few psi over the high limit.
Even if it did lose 3 or 4 or gain 3 or 4 , nobody on this forum can feel that. A 1% change in power is all in your head. Professional race car drivers struggle to feel a 1% change unless they are beside another car.

To be clear, I never said I felt like it lost HP. Let's assume for a minute that this change in car character is not in my head but a real thing, could switching to a 0/40 have revealed some other issue that the 10/60 was helping mask? Reason I ask is that I have a very loud vanos noise on cold starts. 7-8 rattles before a loud clunk all in the first 2 seconds. Wondering if there is a connection? It was present with both types of oil, it didn't start with the swap to 5/40, but if it is a problem could the thin oil have excsaperated it?

Doc, I'm sorry my "flatten out" dyno couldn't solve your problem and made you feel better, but seems like you have a non-oil related issue, like loud clunks at start up and maybe the shop butchered your rod bearings, who knows.

I thought your cam chain tensioner should've fixed the start up clunks? Maybe it's time to get it on the dyno and see if the engine is healthy.

good luck

Doc Oc wrote

To be clear, I never said I felt like it lost HP. Let's assume for a minute that this change in car character is not in my head but a real thing, could switching to a 0/40 have revealed some other issue that the 10/60 was helping mask? Reason I ask is that I have a very loud vanos noise on cold starts. 7-8 rattles before a loud clunk all in the first 2 seconds. Wondering if there is a connection? It was present with both types of oil, it didn't start with the swap to 5/40, but if it is a problem could the thin oil have excsaperated it?

Most cars have that, the noise is because the oil has bled back down to the pan, the valvetrain runs out of control for a few seconds and then when the oil pressure hits it the bang is the slack being taken up in the chains and the lifters slamming back into the cam. It is annoying if not driven everyday but it is not because of thinner oil. If the check valves are leaking it is going to leak with all oils, although the thicker will take longer.
If I start mine everyday it is totally silent, but after 3 days or longer it makes the same clack clack bang noise.

Leonardo629 wrote

Doc, I'm sorry my "flatten out" dyno couldn't solve your problem and made you feel better, but seems like you have a non-oil related issue, like loud clunks at start up and maybe the shop butchered your rod bearings, who knows.

I thought your cam chain tensioner should've fixed the start up clunks? Maybe it's time to get it on the dyno and see if the engine is healthy.

good luck

Why get defensive? You can look for yourzelf, your dyno is absolutely flattened up top. If it doesn't bother you then no biggie

Leonardo629 wrote

Doc, I'm sorry my "flatten out" dyno couldn't solve your problem and made you feel better, but seems like you have a non-oil related issue, like loud clunks at start up and maybe the shop butchered your rod bearings, who knows.

I thought your cam chain tensioner should've fixed the start up clunks? Maybe it's time to get it on the dyno and see if the engine is healthy.

good luck

All of the noises started well before the bearing swap. They were probably there when I bought it but never showed up because I was driving it like a madman the first month. Haven't gotten both tensioners swapped yet unfortunately, we will see on that. I'm still going to run both oils on a dyno for shits and gigs and will post results.

kawasaki00 wrote

Most cars have that, the noise is because the oil has bled back down to the pan, the valvetrain runs out of control for a few seconds and then when the oil pressure hits it the bang is the slack being taken up in the chains and the lifters slamming back into the cam. It is annoying if not driven everyday but it is not because of thinner oil. If the check valves are leaking it is going to leak with all oils, although the thicker will take longer.
If I start mine everyday it is totally silent, but after 3 days or longer it makes the same clack clack bang noise.

Good to know, thanks! So in your opinion is there any point going through the trouble of replacing the tensioner on the passenger side to try to mitigate this noise? And would it be worthwhile to replace the check valves?

Thanks kawasaki, for providing data rather than dismissing the idea. As I said, pressure is key so as long as the pressure remains that's what is imporyant

kawasaki00 wrote

Lifters are driven off oil pressure not viscosity. 87psi is the high limit of the bmw spec. The 0-40 is still on the bypass at high rpm. Liquid cant be compressed therefore the valve lift is still the same. The only way the valve could compress is if the pump could not supply enough pressure to ever get on the bypass. This is not the case of the s65. My gauges have logged 90psi at 8700rpm. That is actually a few psi over the high limit.
Even if it did lose 3 or 4 or gain 3 or 4 , nobody on this forum can feel that. A 1% change in power is all in your head. Professional race car drivers struggle to feel a 1% change unless they are beside another car.

Very well said. Logging these engines with a dedicated oil pressure gauge with various viscosity of oils have all proven one thing: the oil system is capable of maintaining pressures, even with thinner oils. With the thinner oils, the base idle pressure is lower by approximately 8-10 PSI, however it is still above the minimum required oil pressure specification from BMW.

Doc Oc wrote

Good to know, thanks! So in your opinion is there any point going through the trouble of replacing the tensioner on the passenger side to try to mitigate this noise? And would it be worthwhile to replace the check valves?

Changing the tensioner wont do anything, it operates like it should there is just no pressure at the start to make it work as intended.

Malek@MRF wrote

Very well said. Logging these engines with a dedicated oil pressure gauge with various viscosity of oils have all proven one thing: the oil system is capable of maintaining pressures, even with thinner oils. With the thinner oils, the base idle pressure is lower by approximately 8-10 PSI, however it is still above the minimum required oil pressure specification from BMW.

Malek has more dealings in this but I don't think the check valves can be replaced unless the head comes off. Maybe he can chime in here.
A few guys have had it done under warranty and they said it did help the noise, out of pocket that is probably pretty expensive though.

Thanks for the reply. I didn't know where the valves were, just figured it'd be an inexpensive part to replace. So it sounds like its something we just have to live with. Nice excuse to drive it more!

Malek@MRF wrote

Very well said. Logging these engines with a dedicated oil pressure gauge with various viscosity of oils have all proven one thing: the oil system is capable of maintaining pressures, even with thinner oils. With the thinner oils, the base idle pressure is lower by approximately 8-10 PSI, however it is still above the minimum required oil pressure specification from BMW.

Thanks for the reply. Is there anyway this 8-10 psi drop could have a detrimental effect on anything? I know thinner oil gets where it is supposed to go quicker on startup but I'm wondering if this loss of oil pressure negates that at all? And given that psi drop, wouldnt it be wise to go with the thickest 0w40 available if you are going to switch to that weight?

Doc, if thicker is what you seek, Redline 0W40 might be just right for you. I've seen good UOA result from a fellow member who does frequent trackdays, he uses his own concoction of Redline.

Note: 9000mi usage, and low viscosity.
http://www.m3post.com/forums/showpost.php?p=13854994&postcount=58

You can always do half M1 0W40 and 15W50, some mixes TWS with M1 0W40, but I don't like the notion of mixing different brands myself.

Leonardo629 wrote

Doc, if thicker is what you seek, Redline 0W40 might be just right for you. I've seen good UOA result from a fellow member who does frequent trackdays, he uses his own concoction of Redline.

Note: 9000mi usage, and low viscosity.
http://www.m3post.com/forums/showpost.php?p=13854994&postcount=58

You can always do half M1 0W40 and 15W50, some mixes TWS with M1 0W40, but I don't like the notion of mixing different brands myself.

Good link, thanks. I've pretty much decided on redline 0w40 for the long haul but will probably still try tws for the dyno comparo. Do you know why his viscosity is so low? Is it the race oil or does the redline shear that much?