1990 VW 1.8L - Need advice

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We have a very low miles '90 VW Cabriolet just under 37K original miles on the original 1.8L motor.

As far as I know, based on records obtained with the car, it's always had conventional oil. When we got it last summer, I changed it with Castrol GTX 20W-50 per the Viscosity Requirement vs Ambient Temperature table in the Bently Manual for the MK1 platform.

I'm wondering a few things:
1. How often should I be changing the oil in this car? It gets driven ~1000 miles a year in spirts. It will sit 2-4 weeks without being started then get driven 30-100 miles on a weekend day cruising around.
2. Can/Should I switch to full Syth like 0w-40 M1 that I run in my other VWs?
3. Are there risks to switching?

Thanks!
 
I have a 1987 VW Cabriolet that we use like you do but did do a recent trip to Florida. Ours has around 187K on it and still uses no oil. I run Rotella T and a Mann filter The oil is 15-40. Getting 30-34 mpg even running the AC. It is a great little car that we bought in Phoenix. Be sure to replace that timing belt if it has not been done. if it is 18 years old it is probably ready.. Not a hard job if you like wrenching on it.
 
20w50 sounds awfully thick for your environment. I’d use a 10w40 and change it once a year.
 
Those old German motors love viscosity, 20W-50 is fine but I prefer a 15W-40 diesel engine oil for a stouter add pack. Even though the latest Delo/Delvac/Rotella CK-4/SN rated oils have less Zn/P than their CJ-4/SM(L), there's still more than your typical 20W-50 oil which uses the same add pack as an ILSAC-compliant oil but is much less volatile than a xW-20/30.

I'd use Delo, Delvac or Rotella if were you. I doubt your MKII VW is going to Tahoe or up Diablo/Hamilton in the winter - you can get away with 20W-50 as well. But 15W-40 is more of a sweet spot between MPG, protection and easy starting when it gets cold.
 
Last edited:
Originally Posted By: Nick1994
20w50 sounds awfully thick for your environment. I’d use a 10w40 and change it once a year.

And what exactly are you basing that on?

Originally Posted By: ReadTheBook
Castrol GTX 20W-50 per the Viscosity Requirement vs Ambient Temperature table in the Bently Manual for the MK1 platform.

There it is. 20W-50 is what you need unless it will regularly see sub-freezing temperatures. GTX is the classic choice, but nearly any 20W-50 once a year would work well.

I ran M1 15W-50 in my G60 swapped Cabriolet.
 
Originally Posted By: rooflessVW
Originally Posted By: Nick1994
20w50 sounds awfully thick for your environment. I’d use a 10w40 and change it once a year.

And what exactly are you basing that on?
Ok, I’ll change that to 15w40, according to your link

Quote:
This can be quite controversial; positive and negative comments are said about all oil types and brands. Most agreed upon, however, is using 20W-50 in the warm summer months and 10W-30 in the cold winter months, or 15W-40 year-round (those in year-round warm climates can use 20W50 year-round)


It doesn’t get that warm in San Francisco. If it needs 20w50, then VW’s cylinder clearances must be like shooting pool with a rope.
 
Thanks for the responses. I’ll stick to once a year and look for a 15w-40.

I do know about cabby info, but thanks for that..
 
Originally Posted By: Nick1994

It doesn’t get that warm in San Francisco. If it needs 20w50, then VW’s cylinder clearances must be like shooting pool with a rope.

Buslab in Berkeley recommends O'Reilly(WPP, same as SuperTech and Service Pro) 20W-50 for the Wasserboxers in the Vanagons. San Francisco proper is colder than Oakland/Berkeley but the Bay Area once you pass through the Caldecott or north/south of Oakland/SF can get hot in the summertime. A lot of Mercedes and BMW shops as well as the dealer pumped in Castrol or Valvoline 20W-50 as default in the 1980s-1990s, I remember an old 420SEL Benz my family had saw nothing but Pennzoil Multi-Vis 20W-50 until I switched over to Delo 400 when I was starting to wrench.

For some reason like I said the Germans love thick oil, while Toyota and Honda specified 10W-30/40 back then. Now with 0W-XX making its way at BMW/VAG/Daimler, things have changed. I still wouldn't use anything API SM/SN single-rated in a 80-eras Euro car.
 
20W-50 is fine for it but i would use Shell Rotella T5 15W-40, a syn blend HDEO with 1200-ish ppm of Zddp ( assuming it has a flat tappet cam ? )even if it's a fairly tame cam a little extra Zddp is never a bad thing with flat tappets.
 
Originally Posted By: nthach
Originally Posted By: Nick1994

It doesn’t get that warm in San Francisco. If it needs 20w50, then VW’s cylinder clearances must be like shooting pool with a rope.

Buslab in Berkeley recommends O'Reilly(WPP, same as SuperTech and Service Pro) 20W-50 for the Wasserboxers in the Vanagons. San Francisco proper is colder than Oakland/Berkeley but the Bay Area once you pass through the Caldecott or north/south of Oakland/SF can get hot in the summertime. A lot of Mercedes and BMW shops as well as the dealer pumped in Castrol or Valvoline 20W-50 as default in the 1980s-1990s, I remember an old 420SEL Benz my family had saw nothing but Pennzoil Multi-Vis 20W-50 until I switched over to Delo 400 when I was starting to wrench.

For some reason like I said the Germans love thick oil, while Toyota and Honda specified 10W-30/40 back then. Now with 0W-XX making its way at BMW/VAG/Daimler, things have changed. I still wouldn't use anything API SM/SN single-rated in a 80-eras Euro car.

Most German, British and Italian cars up until the early 80s used 20w50 as default.
and 10w40 was probably the most common recomended grade until the early 2000s.
 
Right, and we're talking about an engine that didn't change much at all from it's initial design - in the 70s.

You can run a 15W-40, but don't be surprised if your oil light flickers at hot idle in 90° weather.

It's just the name of the game - these engines take a 20W-50, as you saw indicated in your Bentley manual. If I still had mine I'd flip through the owner's manual and show you the same chart.
 
My Capri's Essex V6 engine ( designed in 1965 ) on a hot 100F summer day will barely, just barely have enough oil pressure on a 10w40 at hot idle, on a 20W-50 Dino it's happy at 1/4 of the way up the o.p gauge at idle.
It recomends 20W-50 for my climate, so can't say the manual is wrong.
 
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