[T3] 73 T-3 oil temp?
willjahn975 at gmail.com
Thu Sep 9 11:03:47 PDT 2021
Jim I understand what you are saying and agree. I don't have an owners
manual yet there is one on Samba. It shows SAE30 and 40. It states there
is an overlap on the oil grade. I see the 30 and 40 , each has a a block
that is solid then each has smaller separate blocks. I assume the solid
block represents the ambient temps best for each grade. If that's true and
since the top of the SAE 30 is even with the bottom of the 40 , this means
to me that SAE 40 is fine from 65 F to over 100F. Also when ambient temps
are concerned back when this chart was made we had a lot less traffic a
lot less added heat on the road that all contributed to the ambient temps,
like I ended up in and the entire reason I posted that.experience.
Here where I live there exist only 2 auto parts stores AutoZone and
O'Reilly . AZ mainly carries synthetic oil and as for or any with zinc
Valvoline 20/50 is it and they have no zinc additives, very little
conventional oil other than STP in SAE 30 and 40 . O'Reilly has better
selection trouble is it's in a very bad area. I can order yet need to spend
over $50 to get free shipping , Amazon won't ship any oil with zinc here.
On Thu, Sep 9, 2021 at 8:17 AM Jim Adney <jadney at vwtype3.org> wrote:
> There's probably no one among us who has not been down the "more oil
> pressure is good" road. Good oil pressure is the ONLY thing a stock engine
> can tell us, but it's important to keep in mind that VW thought any oil
> pressure above the oil pressure switch trip point was okay. That trip
> point is
> something below 10 psi.
> The reality is that the pressure we measure depends on the flow and the
> resistance to flow beyond the point where pressure is measured. So, yes,
> tight bearing clearances will increase pressure, but so would smaller oil
> The degree of lubrication we're getting in our bearings has almost nothing
> do with the oil pressure we are measuring. The oil pressure we measure is
> just an indicator that we are probably getting oil to the bearings. Keep
> mind that if there was a complete blockage of the oil passages after the
> measuring point, we would measure huge pressures, but that would not be a
> good sign.
> The important thing to understand is what oil does after it's delivered to
> bearing. Think about a crankshaft that's perfectly centered in its
> That crankshaft does not need ANY lubrication, but once it starts to be
> pushed off center, that's when we want oil in there.
> The designers of the engine know the directions where the the crankshaft
> going to be pushed, so they design the bearings so that oil will be
> elsewhere. These will be low pressure areas around the crank.
> When the crankshaft spins, it drags the oil around and pulls it into the
> where clearances are tight. The rotation of the crank pumps the oil into
> places where it's most needed, and this pumping produces pressures,
> WHERE IT'S NEEDED, that can be HUGE. These pressures dwarf the
> pressures we have been measuring in the delivery system. I don't know
> actual numbers, but I'm willing to guess that they are hundreds or
> of psi. This is the hydrodynamic pressure developed in a journal bearing
> makes it so effective.
> Going for higher viscosity oil will certainly increase the measured
> pressure in
> our engines, but this may be misleading, as it is bound to lead to reduced
> flow. It also tends to open the oil cooler bypass valve, meaning that less
> passes thru the oil cooler and the result is hotter oil. So thicker oil
> may well
> be counterproductive.
> Thicker oil also requires more energy to pump, and this extra energy ends
> up as heat in the oil. More energy lost in the oil means less energy to
> wheels and higher temperature oil.
> So, all that said, I come back to the fact that while ALL of us have
> down the thicker oil is better road, but it's not that simple. Take a hint
> the engineers who designed and tested our engines over decades. They
> knew the whole story and they put their recommendations in our owners
> manuals. Take a look at yours and see what you can do that sticks to its
> guidance. Yes, keep in mind that we can no longer buy the oil made at that
> time, but we can make thoughtful decisions from what is available today.
> For what it's worth, I usually use a cheap Diesel 15W-40, partly because
> meets older additive standards and partly because it's a multi-grade oil
> doesn't get as thin as most of the auto stuff available today. Bonus:
> tend to run dirty, so I figure this is a lot like our filterless engines.
> For zinc, to
> preserve my cams and lifters, I use a Lucas additive that is very
> Jim Adney, jadney at vwtype3.org
> Madison, Wisconsin, USA
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