Castrol Syntec 20W50 for "Classic" Cars

[Mike Shawgo]

Hi everyone,

Has anyone tried the new Castrol Syntec 20W50 that is supposed to be for "classic" cars?   I tried some in my '71 Eldorado, and it seems to be running smooth and quiet.   I was impressed that Castrol introduced something for classic cars which they say has increased levels of zinc.   Just wondering if anyone else has tried it.

--Mike

http://www.castrol.com/castrol/genericarticle.do?categoryId=82915470&contentId=7032644

[TJ Hopland]

I wonder why they picked a 20-50?    Something a little thinner on the cool side would be nice for those in cooler climates.  Also seems a 50 may be a bit on the thick side if you have a nice tight engine.  I would think a 15-40 would cover more people but maybe that is just me.   

[Mike Josephic CLC #3877]

I have a couple of issues with this "new" product:

-- Using a synthetic oil in our old cars is not the best idea -- they tend to cause leaks
from everywhere.  Also, they afford no advantages vs. regular oils for our useage

-- Why a 20W-50?  This grade was never recommended for cars of our vintage.
The 10W-30 or 10W-40 standard type oil are best suited and that's what our
engines were designed for

-- The "zinc hysteria" -- don't even get me started on this one.  For how often we
drive our cars (not under heavy loads and low mileage) the levels of ZDDP are more
than adequate in today's oils

This is a clever marketing ploy to get you to pay a premium price for something you
really don't need!! (I was in the industry for 35 years, I know!).


Mike

[TJ Hopland]

Anyone see what it cost vs 'regular' oil?   I was at a store today that just started carrying Royal Purple, I did not look real close to see if it was a 4 or 5 quart jug but it was $49.

[Dave Shepherd]

Some of the issues with any multi oil are the temps required before the oil changes viscosity, a lot of our engines do not reach this oil temp and the oil stays thin.  The ZDDP issue is critical for solid lifter engines. Broken in hydraulic lifter engines are less problematic in this area.  But it is cheap insurance to use addt'l ZDDP protection as we cannot see what is going on in there.  I do periodic oil analysis on customers engines and after a rebuild I definitely use ZDDP and cut open the filter after the 1st oil change. 20-50 is somewhat heavy unless the car is started in primarily warmer temps. Some older engines are now loose enough where this is ok.

[RobW]

My 73 owner's manual lists 20W-50 as choice depending on temp range.

[TJ Hopland]

Ya looking at the 73 manual :

20W-20, 10W-30, 10W-40, 20W-40, 20W-50 are listed for 20-100*F

10W, 5W-30, 10W-30, 10W-40 are listed for 0 to 60*F

5W-20, 5W-30 are listed for -40 to 20*F

So its saying 5W-30 is good for -40 to 60 *F?  Why do they have it on 2 seperate lines?
1030 and 1050 are on 2 lines also?

There are notes about 520 not being used for high speed driving, sae 30 only used over 40*F, and 5w30 while operating in Canada.

I also happen to have an 80 manual handy.  It does not have the odd duplicates like the older one did.  10 30 and 10 40 have the same range. 20 20, 20 40, and 20 50 all have the same range just not going as low as the 10's.

I guess I never looked that close at those charts before.  I just do a quick look to see that 1040 is listed and never looked much further.   My diesel only lists 10-30 and 30.  I wonder if that was all there was for diesel back then?  Im running 15-40 now because that seems to be the common all around diesel oil now days.

[Wayne Womble 12210]

Dave,   

I am going to assume you meant the oil stays thick?   No oil thickens with temperature.

[Dave Shepherd]

Wayne, say you put straight 30w in the engine, at 180 oil temp it thins to a certain viscoisty, take 10/30 same situation, that oil is made to change to what straight 30 would be at the same temp, so it is manufactured to become what 30 would be at 180 degrees, but if the engine does not reach that changeover temps the chemical transition will not occur.

[dadscad]

Refined petroleum oil thins and thickens with temperature change, when the base oil cools, it thickens, when it heats, it thins. The grading of the oil is related to the timed flow rate through a specific size orifice at the prescribed temperature. Refined petroleum in a 10-30 configuration has thin 10 weight base stock so it will flow well when cold and added polymers to make it flow like a 30 weight when it reaches the proper temperature. Think of the polymers as spring like coils that contract when cold and expand when heated, The 10 weight base stock is the lubricant, the polymers do not lubricate, they just expand to take up space and make the oil flow as a 30 weight at operating temperature.

Properly formulated synthetics do not require as many additives to obtain the same results. The synthetic can be built to flow freely at low temperatures and still protect at high temperatures with the addition of fewer filler additives. You get more real lubricant at all operation temperatures that better protect the moving parts. This is another reason synthetic oils withstand higher operating temperatures, they don't have the fillers and impurities of petroleum oil that oxidize and break down when heated. Synthetic oils don't thicken and thin as much as refined petroleum oil with temperature change, therefore they flow better at low temperature start ups and protect better at high operating temperature.