VQ35 Hydraulic Lash Adjusters
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Again true, but the starting point of this thread was BTB seeking feedback on someone else's claim that the VQ35's lifters were specifically designed for 5w30 oil. I believe that to be incorrect, but hey, I could be wrong. I just don't see why they'd design the engine for 5w30, and then turn around and allow 10w-40 in the manual. Alas, I'm afraid this is one we're probably not going to get a concrete answer for unless a Nissan engineer materializes from thin air...
Oh yeah...forgot about the original poster. JB has it about right. The lifters generally have to operate over a range of viscosities. The exception being some engine designs with cylinder deactivation. Those tend to be sensitive to viscosity.
Oh dear -- looks like we've got a real mind bender on our hands. The TSB you linked to came out three months after the one I was looking at. I found EG-050-04 (rev 1/06) right on techinfo.toyota.com, their official site, but I had sorted for 04 Prius TSBs only. The later one, EG-018-06, with applicability to all models, mysteriously does not appear amongst the Prius TSBs, although obviously, the Prius engine is listed (NZ series).
Of course, the NZ series, as an I-4, sans electric boost, also powers the little Yaris. So there's an ambiguity.
EG-018-06 also contains a specific statement that Prius owners should refer to the older TSB (EG-050-04), but doesn't specifically say that's because one should follow the 5w30 viscosity recommendation contained therein (edit -- although that's really all that the older TSB says). And again, if it meant this, why would it also list the NZ series engines further down in the "can use 5w-20" box??? I'd be inclined to infer that the later TSB rules, were it not for the Prius-specific reference back to the older TSB.
Well, needless to say, I'm not taking this question back to the dealership. I'd have better luck getting them to explain the theory of relativity...
I'm all ears if someone's got a clearer read on this.
Finally, yes, the more I dig through the service manuals and TSBs, the more I see that this car is full of neat little features. As part of the Atkinson cycle thing, the crankshaft is actually slightly offset from the cylinder bores, so that when the piston is at TDC, the conrod is past TDC on the crankshaft, which apparently allows more efficient conversion of combustion force into rotational motion. And I'm only just beginning to get a handle on how the ECU coordinates the elements of the HSD -- fascinating stuff.
Of course, the NZ series, as an I-4, sans electric boost, also powers the little Yaris. So there's an ambiguity.
EG-018-06 also contains a specific statement that Prius owners should refer to the older TSB (EG-050-04), but doesn't specifically say that's because one should follow the 5w30 viscosity recommendation contained therein (edit -- although that's really all that the older TSB says). And again, if it meant this, why would it also list the NZ series engines further down in the "can use 5w-20" box??? I'd be inclined to infer that the later TSB rules, were it not for the Prius-specific reference back to the older TSB.
Well, needless to say, I'm not taking this question back to the dealership. I'd have better luck getting them to explain the theory of relativity...
I'm all ears if someone's got a clearer read on this.
Finally, yes, the more I dig through the service manuals and TSBs, the more I see that this car is full of neat little features. As part of the Atkinson cycle thing, the crankshaft is actually slightly offset from the cylinder bores, so that when the piston is at TDC, the conrod is past TDC on the crankshaft, which apparently allows more efficient conversion of combustion force into rotational motion. And I'm only just beginning to get a handle on how the ECU coordinates the elements of the HSD -- fascinating stuff.
Ooops, sorry, we're pretty well OT here -- perhaps time for a new thread?
I completely agree with you sir... 10W-40 is the work of the devil.
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