[T3] Stupid question #395 Oil change time?

William Jahn willjahn975 at gmail.com
Wed May 29 15:27:22 PDT 2019

I spoke to Valvoline again and they said you can't mix 20W50 with a 10W40
something about the molecules will not mix. I was told that since they
don't mix and they said this would be true of any multi grade oil you would
get the 20W50 then the 10W40 so the oil pressure would rise and fall.

 All of this is so far above what my brain will process. They do have a 30W
and 40W single grade and said it always is that weight when it comes to
pressure and flow. I always was told or thought a straight weight thins out
when hot at least that's what I've read . So a 20W50 does not get thicker
it just is a resistance to flow and in so it hangs around longer at the

On Wed, May 29, 2019 at 2:24 PM William Jahn <willjahn975 at gmail.com> wrote:

> Jim best I can figure since I lost the book with the mileage when I
> rebuilt this engine in 1997 from 1997  to now is has 35,000 miles on it say
> 36,000.
> When I rebuilt it the oil I used was Kendall 40 W which is what was
> suggested to me , it's also what used in the original engine of unknown
> mileage the odometer was not working. and from what I could see after
> removing all the tin and fan housing and cooler and vent tower it had a lot
> of old crusty oil build up.
>  I don't know why 40 W was suggested yet it was very hot above 90 other
> than a two months each year and on a long freeway run even with 40 W
> Kendall the oil light would come on at idle. That's about what the Bentley
> suggested in the higher end of a tropical climate. I always used SAE 30W of
> 40 W detergent oil. I did until 2005 when every place here stopped stocking
> it at least the Kendall all was left was 40W Castrol yet it did not have
> zinc and if it did is might have been 400 ppm they don't list it on their
> sight. Then I read this VW bug page suggesting 20W50 Castrol talking about
> bugs and vans here is a link.
> http://www.vw-resource.com/engine_oil.html
>  When I just changed the oil a few days ago thought I had 3 qt's of 20W50
> yet had 2 and 8oz so I added 1 pint of 10W40 havoline that I had still
> sealed from the 90's. Here at least when I drive the coldest it is 70 * F
> on start up and if it sits a few days the oil light is one for a few
> seconds. Drove it today it's about 80 on a 20 mile round  trip and @ idle
> the VDO pressure gauge was 25 PSI temp was 150 on the VDO sump sender to
> gauge and the pressure got to 55 psi driving . When first started it was 65
> psi at idle. It does have a working thermostat and flaps. When it's above 90
> I've seen the temp reach 180 yet this is just a guide it's not a true
> reading.
>  I get what you are saying about short trips and 20W50. I do want to have
> the ZDDP . If I understand any of this and I never really cared for multi
> grade oil to be quite honest , isn't it still true the new multi grade oils
> say with the 20 will be 20 W depending of the ambient when I start the car
> and on say an 80 * day might be in the 40 W range and above 90 might be in
> the 50W range. I looked for any place that might sell a 40W and find
> nothing here, everything remotely close to that is something I would have
> to order on line. The other part of my thinking is if the Valvoline VR1
> 20W50 has 1400 ppm zinc yet does not have as much detergent as regular
> Valvoline and I want to bring it down to say a 15W40 and add more detergent
> I might be able to mix in some 10W14 Valvoline I have which has 830 ppm
> zinc and perhaps end up with usable compromise? It seems a bit difficult to
> know just how much of each will get me there.
>  You are using a 20W40 then it was gone and use 15W40 diesel oil. Are you
> thinking of going back to a single grand like 3oW or 40W since you don't
> drive your VW's in the winter?
> William
> On Wed, May 29, 2019 at 8:09 AM Jim Adney <jadney at vwtype3.org> wrote:
>> On 28 May 2019 at 14:27, William Jahn wrote:
>> > I'm lost on all the terms on oils. Since I've been using 20W50 Castrol
>> it
>> > has no zinc or ZDDP. The Valvoline 20W50 has 1400 ppm zinc and from what
>> > I've read the zinc basically is a metal coating that stays on the
>> bearings
>> > and other moving parts. Would this oil be good enough?
>> Since all your trips are short, your engine spends most of its time in
>> warmup,
>> so I'd think that 20W-50 oils would be a very poor choice for you, unless
>> you
>> think this engine is old and very worn out. I would look for a straight
>> SAE 30
>> that has more than 1200 ppm of zinc, or just any 30 to which you could
>> add a
>> bit of that Lucas or GM EOS to it at each oil change.
>> VW recommended straight weight oil for our cars under almost all
>> conditions. I tend to forget that VW continued to recommend them even
>> long
>> after they were first introduced. Multi-grade oils are a much later
>> improvement that we really don't need.
>> I looked for a Tractor Supply Company near here and found one. They have
>> their house brand (Traveler) of SAE 30 in 5 qt plastic jugs for $9. I
>> don't
>> know about the zinc content yet, but I submitted a question. That's an
>> excellent price, which will help make any additive affordable.
>> --
>> *******************************
>> Jim Adney, jadney at vwtype3.org
>> Madison, Wisconsin, USA
>> *******************************
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