oil for rebuilt vw 1.8

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Jan 4, 2004
I am basically a VW and oil newbie and easily confused so please bear with me.

I have tried to read up on this a little but still very confused on all this, especially since I hear/read different opinions.

Application: VW 83 Rabbit GTI, rebuilt high compression 1.8 motor with about 5k miles.
Location: Portland, OR

I am currently running a dino 20-50 (for no particular reason other than it was recommended) and strongly thinking about moving to a synthetic, possibly Amsoil. I have heard I should run 10-40, 15-40, 20-50. I am currently looking at Amsoil since I have heard good things about it.

I stopped by GI Joes yesterday and saw they had the following.
AMO 10W-40
AME 15W-40
ARO 20W-50
TRO 20W-50 (Series 2000)

I did not see the XLO 10W-40 mentioned on the Amsoil website.

I don't really understand the differences between these and what would be "best" for my car. My gut feeling is that any of them would work well, but also, one of them is probably the "better" way to go for some reason.

Any suggestions as to what I should use (Amsoil or even other brands)? Would it be better to go with say a 10W-40 vs a 20W-50 in a fairly new (rebuilt) motor?

Also, any explanation or reason for making a particular suggestion is very welcome.

older vw engines run pretty cool oil temps compared to most engines. your choice of viscosity is up to you, however you wouldnt need a oil designed for high tempatures.
whats your static compression ratio? using aftermarket cams or other parts? this can effect the advice given.
My Bosch mechanic uses Castrol RX 15w-40 in all VWs. HDEO has aways been a part of VW and Porsche specs. For a synth I'd use the Syntec 5w-40 from Belgium, available at the VW dealer or many Speed Shops. AutoZone has the German Syntec 0w-30 the SLX or GC also there is the Syntec 5w-50 in a pinch. I would use the HDEO like: Delvac, Dello 400, Pennzoil Long-Life or Rotella 15w-40 unless the climate was too cold, otherwise a 5w-40 synth...Rotella synth is easy to find at Wal*Mart for $3 a quart. Excellent $2 Syntec Blend 10w-40 is ACEA A3 approved (Euro specs) and will be better in moderate cold then the 15w HDEO oils.
I don't see the need to use a 20W-50 motor oil in a modern mechanically sound engine. If you don't have an oil consumption problem then I would suggest using 10W-30 Amsoil or 10W-30 Mobil 1 SuperSyn. You didn't list 10W-30 Amsoil as being available at GI Joe's so if you want to try 10W-30 Amsoil then you may consider ordering from one of our bobistheoilguy site supporters.
10W-40 Amsoil will be OK but there will be a penalty in fuel economy and in my opinion very little benefit over an ACEA A3/B3 rated synthetic 10W-30 motor oil.

I would expect if you were to go to a fully synthetic 10W-30 oil (from the current 20W-50) you will have a fuel economy gain of at least 3% if not more as well as cooler oil temperatures. Cooler oil temperature will mean that all of the various gaskets and seals in your engine will last longer. You will also notice faster cold starts with a thinner oil. More benefits to a thinner oil are less strain on your battery and starter motor.

Other good choices for synthetic oil are Mobil 1 SuperSyn 0W-40 (ACEA A3/B3/B4), Castrol Syntec 10W-30 (newly rated ACEA A5) and Casrol Syntec 10W-40 (ACEA A3/B3), and Valvoline SynPower 5W-40 (ACEA A3/B3).

If you do experience higher than acceptable oil consumption with a 10W-30 motor oil you can always switch to 10W-40 or 15W-40 Amsoil, 5W-50 Castrol Syntec or 15W-50 Mobil 1 SuperSyn.

In my humble opinion Amsoil makes some of the best motor oils that you can get and I use it in two of the three car that I maintain.

[ January 18, 2004, 03:26 AM: Message edited by: Sin City ]
I listed the European ACEA ratings in my previous post since they are far more demanding than the rather weak API SL and SJ standards. The ACEA A5/B5 and A3/B3/B4 standards are for "high performance engines" and go far beyond the current North American API standards for passenger car motor oils. All of the oils listed in my previous post meet at least some of the "high performance" ACEA specs.

[ January 18, 2004, 03:37 AM: Message edited by: Sin City ]
I'd use 10W-40 in the old Rabbit. That's what I used in both my Sciroccos. One was an '80 GT with the 1,6l motor, the other one was an '89 (Euro) GT with the 1.8 l engine. 10W-40 worked very well in those engines, and the Rabbit's motor should be similar. I wouldn't be dumping anything thinner than an 10W-X in there.
The 10w-40 and 15w-40 are very similar ...

I'd use whichever one is less expensive - that would probably be the 15w-40. Ten years from now if you still have this engine, I'd run the S2000, 20w-50 in warm to hot weather ....

Dixie Synthetics
Now that I think about it maybe 10W-40 or 15W-40 Amsoil would be better than 10W-30 since some VW's are known to have fairly high oil consumption by design. I still think that 20W-50 is too thick for anything but racing conditions, hot weather, or an old worn engine.

Stilly, welcome to the forum!

[ January 18, 2004, 09:36 PM: Message edited by: Sin City ]
I was told the "actual" compression was 11.2:1. My understanding is that there are a couple compression numbers and the guy who had this motor before was not sure whether this is the static one or not, and he was not sure the other number.

The rabbit is CIS with a recurve distributor in lieu of knock sensor. It has a g-grind cam.

Sin City:
GI Joes did have a couple different 10W-30, 0W-30 Amsoil options. I assumed they would be too light and did not mention them.

I got 5 quarts of 10W-40 over the weekend, they had it on sale $1/quart. My current plan is to change from dino on my next oil change and then change oil again after 5-6k miles to help flush the dino/syn mix. Does that seem reasonable? Change sooner or later when I switch over?

Thanks for all the feedback.
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