Synthetic 20W50 for Corvair

Not open for further replies.
Jun 30, 2004
Speedway, IN
Hi all...I recently found this forum, and it's great! I've learned more about oil in the past week than I've known for my 36 years!

With that, I've decided I'm switching over my '93 Caprice 350 to M1 (10/30 summer, 5/30 winter). I've been running Phillips 66 Trop Artic (only 'cause I'm a stockholder!) every 3K, but decided through this board and my brothers to go M1 and extend my drain intervals to 5K. It just turned over 200K last week, so I'm hoping this'll add to its life.

But, my weekend toy is a '65 Corvair, 110. I have been running, again, Phillips 15W40 HD-II in the cooler months and Phillips 20W50 Racing in the summer. 15W doesn't do the best in the summer with its tired engine as well as the heat the oil takes in a Corvair, so that's why I run 20W50 in the summer months. I've also decided to switch to synthetic for the Corvair too, but I'm still wanting to put a 20W50 synthetic in it for the summer. What brands (I wish M1 had a 20w50!) are OK and what should I avoid?? I usually put about 3K miles on the car per year (Weekend Warrior!). My local Advance has Red Line and Auto Zone has Valvoline Syntech, but the pickin's are slim for other 20w50 syns. Thanks in advance!

Pat B.
Speedway, IN
Pat, I'm a synthetic oil user myself, but with the age of the car and 3K per year, you might just want to stick with what you are currently doing.

I wouldn't recommend a switch unless a lot of other factors are known.

Don't see a real benefit for you, plus I have concerns about seal leaks on a 65 and it would be expensive to maintain good oci interval with a syn at 3k per yr.

I wouldn't jump on the syn bandwagon yet with the Corvair.

On the Caprice, with 200K, I don't think you'll have a problem, but I fail to see a benefit either at this point. You'll probably have some consumption issues with M1.

[ July 08, 2004, 01:15 PM: Message edited by: haley10 ]
I would be a bit leary of the effects on seals with 200,000 mi of Dino use. I Think I would at least consider a Auto RX treatment before switching to synthetic.

I do not know the formulations on the Phillips Branded Oils but the Motorcraft and Conoco Hydroclear products by the same company are some of the most highly regarded Dino Oils on the market here. I myself consider their 5W-20 and 5W-30 oils some of the best values on the market as they are essentially Semi-Synthetic at Dino prices and apparently very well built.

Have you considered doing a couple of UOA? I bet you could find a good Dino (Maybe even your current one if its anything like MC or Hydroclear) that could go 6000 mi pretty easy if you put on a pretty significant amount of highway miles.

If the 20W-50 Racing is a true Racing oil it has a very low detergent level and is not a good choice for street use. However some manufactures simply use Racing as a marketing term.

15W-40 HDEO are generally pretty thick with very robust additive packages. Close to a 50 Weight and formulated to be extremely shear stable so unless you have a leakage or use problem you might consider using this year round in the Air-Cooled F6. I do know that Mobil Delvac 1300 is the most stable conventional Dino Oil I have ever used although I have by no means used them all.


[ July 08, 2004, 01:13 PM: Message edited by: Gene K ]
Gene, For what it's worth, I pulled up the specs on the oil from Phillip's website:
20w50 "Racing":
These are both in pdf. I don't know if these numbers mean diddly or not.

I'd say the Caprice is 50/50 highway/street miles, based on my trip to work. I suppose a UOA would tell me for sure how the Phillips does. I've not read a whole lot about Phillips in the archives. Historically, and this goes out to anyone with an answer, can dinos go 5K and still be OK?

I prefer to be conservative, but we have seen very good dino can absolutely do 5K. If your engine is in good shape, I'd bet the Trop-Artic would show you some excellent numbers.

It's not widely marketed, but I would think it is probably excellent.

Rather than assume and switch, you could just stay with the program and do a uoa and see how it is really doing.
I guess you visited my website! I heard Ralphie on the radio this morning here in Indy. I wish I'd have known...I would've driven my Vair to the station for a pic with him.
haley, As for the 200K Caprice I'm happy to say I don't have to add anything between changes (Probably just guaranteed myself a catostrophic failure tonight on the way home by mentioning that), and for a full size Chevy with that kind of mileage, I can still get 24mpg out of it on the highway.

As for your earlier thoughts on the Corvair, I've been a little skiddish about going syn on it in the past, simply for the seals issues that are inherant with a Corvair. Right now, it's pretty tight with the exception of a crank seal. I used Viton o-rings for my pushrod tubes a couple of years ago. For Corvairs, that is where they're most likely to leak first, but the Viton has eliminated that.

But with what I've read so far, I'm thinking maybe I should just stick with what's got me here for both cars.

Pat B.
Pat it appears that the 20W-50 is a street oil with "Racing" used to signify that it is a High Performance Oil with some extra barrier agents including Moly.

I see nothing wrong with using this oil in your current application.

Although there is some discussion about the accuracy of the test the one VOA I can locate of Phillips TropArtic Turbo 10W-30 shows a TBN of 13
That is HDEO territory!

Although a high starting TBN does not absolutely mean that a oil is good for extended drains and will hold up well it certainly does not hurt.

MolaKule seems to think this oil has some of the new Borate Esters in the formulation which explains the high TBN with a relatively average amount of Calcium and modest amount of Moly. In short this would be a excellent oil to try running a UOA on after 5000 mi or so. I would not be suprised if this oil held up very well with longer drains than that.

Also if you can locate the P66 HDEO Super HDII in the hard to come by 10W-30 grade that might make a killer extended drain dino oil for the Caprice as well. Just make sure the bottle has a SJ or SL rating. By looking at the data sheet it was hard to tell if the 10W-30 and 15W-40 carried different S* ratings or if the 10W30 did not have one.


[ July 08, 2004, 04:34 PM: Message edited by: Gene K ]

Pat in Speedway:
What brands (I wish M1 had a 20w50!) are OK and what should I avoid??

Mobil has a Mobil 1 20W-50.

[ ]


The Mobil 1 V-Twin 20W-50 is made with Harley-Davidson in mind, but it has a very high flash point

Flash Point (ASTM D92) °F 518

and a very low pour point

Pour Point °F -60

It's an API SH oil, so the additive levels are higher than current SL oils, and it's formulated without any VI booster. For an air-cooled engine it sounds ideal.

The only downside is price.

$40.50 for a six quart case plus shipping (around $9) is what one on-line retailer is charging.

I'm still an oil rookie here, but is the only diff between the 15w and 20w the flow at startup? The 50 weight aspect of both would be the same, right?

Correct. The 100 C viscosity is still a 50 weight, but acts as if it were a 15 weight in cooler temps.
Thanks everyone for the insight today. Not sure what I'll do yet for my next changes...thinking status quo might be in order.
Without opening up a can of worms, but would a home brew of M1 and the P66 improve the P66 or would that just screw up everything? Stick with one or the other??
I'm still an oil rookie here, but is the only diff between the 15w and 20w the flow at startup? The 50 weight aspect of both would be the same, right?

Oh, in my initial note I meant to say "Valvoline Synpower". My bad!
I'd think that some of the "Oil for air-cooled VW?" threads could shed some light on good Corvair lubes as well...

Originally posted by Pat in Speedway:
I guess you visited my website! I heard Ralphie on the radio this morning here in Indy. I wish I'd have known...I would've driven my Vair to the station for a pic with him.

Now that would have been a truly special picture.

About a year ago I was cruising along on I-10, and on a long wet bridge came up on a beautifully kept blue 'vair. Without warning (or apparent provocation), the thing just suddenly broke its tail free, and it magestically rotatated about 90 degrees. From my perspective, safely ensconced in my six-airbag, ABS, traction and skid control equipped V-6 Camry, I watched in amazement as the driver, cool as a cucumber, fought the thing back and forth a few cycles, got it back, and then drove on down the road as if nothing had happened. The only thing that interrupted my enjoyment of the show was having to dodge a couple other motorists as they paniced trying to avoid this guy. I could almost envision Ralph standing there on the guard rail, shaking his finger (
) and bellowing out, "see, I told you so, unsafe at any speed!!!"

OK, now, back on topic, I'd just recommend being very careful, not only with driving this car, but also with making rapid changes to an oil use program that has obviously worked very well for you up to this point. I'm not saying not to switch, just maybe do it quart at a time, and ARX is probably a good idea too.
Not open for further replies.