Excellent choiceI ran short oci for first couple changes with valvoline EP and then Quaker state ultimate both because of the higher moly that I thought would help with breakin. Now at about 9500 miles thinkin of goin with Mobil 1 esp and staying with that since it’s easy to find and rated api sp
Yeah, the estimates in that spreadsheet are more of a "standardized" VII content assuming the same VII type, but what matters in terms of the oil's performance is not the actual percentage of VII, but the difference in high shear viscosity between grades.Remember, Gokhan's estimates were just that, estimates, and there were many oils that clearly didn't function with the estimation function, yielding wildly off-side results.
I saw your cold weather oil pressure test that you linked in another thread recently, but I interpret the results differently than you do. An oil pump bypass may start bypassing at a lower pressure than the nominal bypass pressure rating, and pressure can also rise much higher than the bypass pressure rating at higher rpm.What temperature are you considering winter conditions? Because both my vehicles don't always go on the relief during the winter months. Yes, my Jeep does when it gets down around -15C or lower, but we do not see those temperatures consistently all winter.
HTHS, which, we unfortunately don't see very often anymore. The point being, I'd be careful basing anything off those calculations, since blending doesn't typically follow the methodology necessary to validate that generalization. The Mobil examples illustrate this quite well.Yeah, the estimates in that spreadsheet are more of a "standardized" VII content assuming the same VII type, but what matters in terms of the oil's performance is not the actual percentage of VII, but the difference in high shear viscosity between grades.
Yes, you can overdrive the bypass, which I've seen many times with SBC's with HV pumps in stock clearanced engines. My buddy's dad made that mistake, pump had a 55psi relief and it would regularly produce 75psi on a cold start, as the relief couldn't pass the necessary volume of oil to keep system pressure at the relief pressure.I saw your cold weather oil pressure test that you linked in another thread recently, but I interpret the results differently than you do. An oil pump bypass may start bypassing at a lower pressure than the nominal bypass pressure rating, and pressure can also rise much higher than the bypass pressure rating at higher rpm.
The engine doesn't have a variable discharge pump, it's a standard crank driven PD pump. The Pentastar engines have a vane pump, obviously, that's a different animal. The action of the pump shearing the oil is going to immediately heat it and reduce the viscosity, as is the act of compressing it. So, even if we assume your 1,000cSt figure for the oil in the pan is accurate (visc calcs aren't accurate below ~0C), as soon as it enters the pump, that's no longer the case. This is also why the bulk oil temperature increases so quickly, as the cold oil is acted upon by the rotation of the camshaft, crankshaft, rods, rockers, pistons...etc, then goes back into the pan, rapidly increasing the bulk temp.On the initial cold start at -18 C, the oil pressure peaks at the bypass rating of 65 psi, then settles to 62 psi, but even at 62 psi, the oil pump is still bypassing. It may even be bypassing when the oil pressure is 59 psi at 30 C oil temperature. You'll be able to tell when the pump stops bypassing when the pressure starts dropping more sharply as the oil temperature rises.
If we assume that the oil pump was not bypassing at 30 C and 59 psi, with ~100 cST oil, then at -18 C with ~1000 cST oil, the oil pressure would be 10 times higher, or around 590 psi, if the flow rate was the same. Restriction and pressure rise roughly linearly with viscosity at a given flow rate (Poiseuille's law). This all assumes that the engine doesn't have a variable discharge oil pump.
I'll see if I can get you some more data from my Jeep. I'd consider my 6.4L pretty typical of an engine with a crank driven PD pump and its pump is higher volume than many other examples. I know the Subaru's have higher volume pumps, what's the relief pressure on them?The chart here below an example of the non-ideal behavior of an oil pump bypass. It shows that even when the pump is in bypass, the pressure changes a bit with changes to oil viscosity. It also shows the linear relationship between viscosity and oil pressure when the pump is not in bypass (80, 100, and 120 C data points at 1000 rpm).
On this engine, the oil pump is bypassing at low rpm whenever the oil is colder than 80 C. This isn't the most typical example, but the oil pump on my Subaru for example is still bypassing at high idle with the oil at 40-50 C. I doubt there are very many automotive engines that don't bypass oil at 10 C, unless they have variable oil pumps.
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Yeah, 1,000 cST was just a very rough estimate. A VI calculator puts a 5W-30 at 2,600 cST, but when oil is this thick will be fully shear-thinned which will lower the viscosity. I don't think the oil pump contributes that much to oil heating. On my car it can take 30 seconds for the oil temp sensor located at the pump outlet to go up more than 1 degree, after which the temperature starts to rise more rapidly (though I haven't tested this in extreme cold). Most of the oil heating is probably in the journal bearings, pistons, and head.So, even if we assume your 1,000cSt figure for the oil in the pan is accurate (visc calcs aren't accurate below ~0C), as soon as it enters the pump, that's no longer the case. This is also why the bulk oil temperature increases so quickly, as the cold oil is acted upon by the rotation of the camshaft, crankshaft, rods, rockers, pistons...etc, then goes back into the pan, rapidly increasing the bulk temp.
The pressure relief setting on my WRX is 102 psi, though Subaru engines more typically have a spec of 75-90 psi , with high flow rates of usually around 60 L/min. The cold idle speed is high as well at 1,800 rpm (due to modern emissions standards), which also contributes to the bypassing on a cold start.I'll see if I can get you some more data from my Jeep. I'd consider my 6.4L pretty typical of an engine with a crank driven PD pump and its pump is higher volume than many other examples. I know the Subaru's have higher volume pumps, what's the relief pressure on them?
You can work CCS visc backwards, it doesn't give you KV, but you do end up with a CCS viscosity figure. You halve it for every 5C, so the Ravenol was 4,560cP at -35C, so it would be ~570cP at -20C, using this method. If we wanted to compare this to a PAO base oil, KV -40C for SpectraSyn8 is 19,000cSt, while CCS is 4,800cP at -30C (Brookfield is 17,590cP at -40C).Yeah, 1,000 cST was just a very rough estimate. A VI calculator puts a 5W-30 at 2,600 cST, but when oil is this thick will be fully shear-thinned which will lower the viscosity. I don't think the oil pump contributes that much to oil heating. On my car it can take 30 seconds for the oil temp sensor located at the pump outlet to go up more than 1 degree, after which the temperature starts to rise more rapidly (though I haven't tested this in extreme cold). Most of the oil heating is probably in the journal bearings, pistons, and head.
Wowzers, that's like Cleveland SBF relief stuff right there, lol!The pressure relief setting on my WRX is 102 psi, though Subaru engines more typically have a spec of 75-90 psi , with high flow rates of usually around 60 L/min. The cold idle speed is high as well at 1,800 rpm (due to modern emissions standards), which also contributes to the bypassing on a cold start.
Here's a video of a Subaru engine in bypass at cold idle with 40 C oil. I think the bypass setting is around 85 psi on this engine. The oil pressure hits 140 psi when the engine is reved up. I'd be interested to know how much higher it can get when the oil is thicker. Needless to say, I've started to pay more attention to burst pressure specs when choosing an oil filter.