Datsun Roadster Forum-311s.org

My repair manual recommends 20 weight oil for the SU carbs. No one has it. What should I use? 10-30? Also what is the best way to buff out those cloudy patches in the ragtop windows Thanks...

I use ATF(automatic transmission fluid) red fluid in all of my SUs including the Z car. Stuff works great and is readily availabel. As to buffing out old soft top windows here is a product called Hawg Wash that is suppose to be pretty good. You can visit their website here http://www.hawg-wash.com/scoffplpokit.html I have never used the stuff before so I am only going off of what several people at work told me.


Steve

A friend of mine (checking my oil) exclaimed that they were low. They are dripping with oil. How do I know if they are low? How much do I put in? I feel funny asking, being that I've owned this car for 6 years and another before that. I've always just made sure that they don't dry out.

They do not take much. When you remove the plunger you can look down into the oil hole. The plungers act as a dip stick and you can check them that way. If you get too much in it will spill out and should not cause any major performance issues. No dumb questions here-just some occassional dumb answers on my part.

Steve

TTTTTTTTTTTThanks BBBBBBBBBBBro

Different engines and different climates dictate different oils. As Steve suggested, ATF is great for most folks. I have used Hydraulic Jack oil (a little more viscous than ATF) as well as Marvel Mystery Oil. I like MMO the best.

As far as how much to add, Steve again has it right. The plungers do have marks so it is the dipstick as well as the damper. Don't sweat getting it too full - the oil going through into the carbs won't hurt things.

I recently had a "Classic MG" mechanic (they also use SU carbs) tell me he uses Marvels Mystery Oil. He said he measures by dropping the plunger back into the hole and if the oil "catches" the plunger about a 1/4 inch before it reaches the bottom, its perfect. Thanks guys! Mark

I found some at Moss Motors in their catalog for MG. As I remember, it was about $4.00 for a bottle that will probably last for years.

Good Luck,

Ivin

I agree MMO is the best for overall performance. First you should decide what you want your car to accelerate like the oil serves the purpose of a regulatory fluid the thicker the fluid the more linear the power application because the rising of the carb internals is slowed down. In my street roadster I use about three cc's of mmo power comes on smoothly, in my race car I only use about three drops per barrel but I want the barrels to pop up and allow me to get a lot of power at once ..not very linear and not recommended for street driving not enough oil can cause the barrels to bounce ...yikes

Hope this makes sense

Just want to add to what russell wrote:

311TONY423,

In case you don't already know, this oil is related to
the air/fuel mixture on acceleration(at constant speed, it doesn't matter/not related).

The heavier the oil, the more fuel you'll get on acceleration.
The lighter the oil, the more air you'll get on acceleration.

If your engine 'sputters' on acceleration, try a heavier
oil.
Running too heavy an oil will cause you to run rich,
too rich will hurt performance and fuel economy.

If you don't end up getting the performance oils recommended
by others here, be sure to get a base 20 oil.
20-30. The 2nd # is the viscosity at HOT temperture.
The carbs don't get hot enuf for this to be significant.

What a great discussion on such a simple topic. I have used ATF in the four seasons of the mid-west and here in California with great success but I need to give the Marvel Mystery Oil a try. In my race car I do not use any oil. As Russell mentioned-not recommended for a street car.

Steve