I read part of the long post on engine oil grades

[blues90]

I also read the post on how the late cases with 2 valves. Oil pressure relief and oil pressure regulating .

I'm not here to debate or post opinions.

When I rebuilt my engine in 97 I checked both valves and neither were stuck yet I had new valves and springs so I replaced them .

This is my question. Many said running 20/50 was to thick the oil would never flow through the stock cooler. I broke in this build all stock 1600 with 40 weight Kendall then is vanished and since I don't know exactly how many miles I have racked up since then , say 50K max . Since Kendall went away I've been using 20/50 Castrol conventional .

If it is true that using 20/50 will never allow flow through the cooler and now I decided to use 10/40 or even 10/30.

For arguments sake and the thinner oil does flow through the cooler wouldn't any crud that might exist in the cooler be washed out and ruin the bearings?

All I have to go by is a VDO 80 PSI oil pressure gauge and a VDO oil temp gauge. The pressure sender is a 7 PSI light with the Gauge so it's 2 contacts and the temp gauge is 120 to 300 F .

Odd thing is today I checked the pressure sender and instead of 10 ohm it read 19 and if I checked the sender to ground I had 19 ohm should be 0 . Once I started it and ran it for a few minutes everything was back to what it should be. I do realize these senders are not all that accurate , I just use them as a base ( what I know reads do not worry) .

Most of the time I do not drive very far so the temp gauge stays at 120 F when I have driven say 10 miles in above 90F it hits 165 to 170F . My pressure gauge as soon as I turn on the key read 10 PSI and these gauges are not linear so I can't subtract 10 PSI . Cold it reads 60 PSI 1000 RPM , warm it drops to 40 PSI 1000 RPM and when oil temp is near 170 F 20 PSI . At 2500 RPM hot it's close to 45 PSI .

Like I said I know these gauges are not exact .

Should I just stay with 20/50 ? I have no way to check for actual oil temp and pressure . I change oil at 2500 miles and add when needed . Last time the screen was clean and the plate had a tiny film I could wipe off , not metal flakes. If the oil light goes off at 7 PSI , if the car sits for 3 days it takes 2 seconds for the light to go out and it never comes on when the oil is near 180 on the temp gauge at idle.

If asking this is beyond the rules well lock it.

[raygreenwood]

[Sqrbckguy38]

I used to run 20w/50 in my fastback when I lived in so cal. I never had issues with the oil. Now I'm living in Utah, and it's much colder, I run 10w/40 instead. Nobody ever told me about crud building up in my oil cooler, and several times I've used a manual pressure gauge to check my oil pressure at the cooler. It was usually about 35psi @ 1500 rpm and would not increase much more than 5 or 10psi at higher rpm. Can't say much about the oil temp, I only knew it wasn't really over heated.
_________________
It's not the fall that hurts, it's the sudden stop at the bottom.
69 Square needs love, even after 15 years
70 Fasty former dd, now my daughter's
67 Beetle, Opal

[W1K1]

basically it comes down to running an oil that flows easiest and doesn't trip the oil light when it's hot.
10psi per 1000 rpm is the rule of thumb. You want oil flow to cool the engine Not high oil pressure that trips the cooler bypass. every engine is different there is no perfect oil viscosity for everyone.
_________________
http://www.thesamba.com/vw/archives/manuals/jim_martin_engine_build.php

1973 super
1965 squareback 1500E
1971 bay window westy- subi swap

[blues90]

I'm not sure about the miles on this engine since I rebuilt it in 97. I wrote down the date and miles yet lost the the book I recorded it in.

Crud building up in the cooler was something that crossed my mind while reading the extremely long oil thread and also reading the thread on how the oil system works with regard how the later 2 valve system works. I have no data or idea if some or no oil runs through the cooler for an extended period of time if any build up/crud would result.

That topic as far as I could tell was done on 1600 beetle engines using valvoline 10/30 and based on the difference between 26 mm and 30 mm oil pumps. Not only is it a different cooling system air flow wise than a type 3 it was 3 different engines and they said they didn't know how much oil was flowing through the filter just that it was based on cooler temps by feel. There is no way to feel an oil cooler temp that I know of with the cooler enclosed in covers.


Based an me using 20/50 was a site I ran across years ago a VW site with info on air cooled buss and beetles running in hot climates . It was said Castrol 20/50 GTX resulted in cooler engine temps. I have no idea if these engines had early or late cases, there was no reference to cooler bypass valves. If i recall I started using 20/50 in 2009 before that is was 40 weight Kendall. I recall going to Autozone and getting Castrol 40 weight then read about how 20/50 held up better.

To be honest there are all sorts of claims and claimed experience on what grade (multi/straight) and what type (synthetic/conventional) base oil to use. The additives that determine a multi-grade are synthetic.

[Max Welton]

If you use a detergent oil (most all are these days) and a filter you shouldn't have to worry about crud building up anywhere on the inside of the engine.

Max
_________________
1967 Type-3 Fastback
Under the Knife https://shoptalkforums.com/viewtopic.php?f=24&t=151582
Home Stretch https://www.thesamba.com/vw/forum/viewtopic.php?t=767836

[Donnie strickland]

By 1975 VW was recommending 20W-50 for temperatures of 15 degrees Fahrenheit and above:

However, didn't the 1975 and later engines no longer have the oil pressure control valve? Weren't those engines relief valve only?
_________________
71 Elm Green FI A/T Squareback

[Glenn]

Please use one of the existing topics.

Also you did not tell use the condition of the engine other that it was rebuilt 20 years ago.

Official "What oil / additives should I use" topic

The importance of choosing the correct oil weight.

Here's my 2¢:
Run the thinnest oil needed. New engine with tight tolerances should use a thin oil. Old and worn engine can use a thicker.
_________________
Glenn
74 Beetle Specs | 74 Beetle Restoration | 2180cc Engine
"You may not get what you pay for, but you always pay for what you get"

Member #1009

#BlueSquare