Which OIL is Best?

[grantf]

I am no expert and still unsure about the best oil to use, but I stay away from synthetic in my car. I have heard that synthetics are a bad idea in older high mileage autos.

[oldhemi]

My opinion is that the BEST oil has three primary characteristics:

1. It is clean

2. It has been in your car's engine less than six months

3. It is the appropriate viscosity for the current outside temperature.

(e.g. no 20W50 below 10 deg. C and no 5W30 above 40 deg. C)

WM beat me to my post!

One Caveat from me and YMMV, I put that new-to-the-market, hyped Mobile 1 in my 260Z back in late 1976 - the car had maybe 25K on it. That stuff disappeared in my car! I always went with 10-40 dinosaur goo after that!

My oil gauge sender broke at the same time - coincidence? Never had a problem with burning or disappearing oil or pressure after I switched back.

A lot of guys that run the old SOHC4 750 Honda's run Rotella for the very reasons that Escalon posted. And they also have the yearly oil wars. Interesting tidbit: that motorcycle came out at nearly the same time as the original 240Z!

Since we bought our Dodge trucks new in 1996, I have been running a blend in my V10 and a full synthetic in my wife's 360. When changing oil, mine comes out a little dirtier than hers. A couple of times I ran pure dinosaur goo and my oil was black and thin. I have nearly double the mileage. I hear that the synthetic stuff is not as sensitive to AGE, which seems to be true. Some years, my wife's truck does not even do 2k miles. So, it might be 2 years before I change her truck's oil! It still comes out pretty clean. But I could be dumb on this truck deal. :stupid:

Edited March 21, 2010 by oldhemi

[Walter Moore]

I am no expert and still unsure about the best oil to use, but I stay away from synthetic in my car. I have heard that synthetics are a bad idea in older high mileage autos.

I have never had a problem with synthetic oil in any car, regardless of the mileage, PROVIDED it met with the three requirements in my earlier post.

[Arne]

I ran nothing but synthetics in my old E21 323i, which had over 330,000 km on it when I sold it. No issues with oil over the 5 years I had it. If your car's gasket or seals are marginal, you could see increased leakage. But on a well-maintained engine you should minimal issues, if any.

[mattbibbey]

Loads of good advice here guys thanks. Some amusement too . It' seems to be a purely personal choice but there is quite a lot to think about. I am rebuilding 2 engines at the moment so I suppose I'll know which oils are best for those when they're apart?! I think I will put Castrol Classic in my current engine for the next oil change and see how it goes.

Cheers again everyone who offered help etc here.

Matt

[Nigel1943]

Just an observation from the forgoing posts but I'm under the impression that Nissan originally built their engines with "wider" tolerances to accomodate the then available oils, ie 20/40 or similar. Rebuilt engines might be different tho.

[ChrisZ]

I second this explanation and reasoning. I live in Arizona so I use VR1 20W50 as it gets rather hot here in the summer. My only advise to you is once you choose an oil stick with it. Don't switch back and forth.

Jan

And i third this, i went with a oil made for diesel engines when i broke in my re build engine, it contains ZDDP, can't remember the viscosity, but i have no preassure issues and no leaks.

Chris

[sblake01]

The viscosity would be important. Especially in the case of a rebuilt engine as Nigel mentioned in post 18. Diesel engine oil has more polymers and detergent additives allowing it to keep more combustion residue in suspension for a longer period before being changed. Seems to me that would create a sludge problem especially if your engine is rebuilt with tighter than stock tolerances. It's been debated many times but in my opinion, I'd stay away for diesel oil in a gasoline engine.

[bpilati]

Pick a brand of fully synthetic oil and a quality filter. I use Amsoil, but Mobil and some others are good too. Don't go out and buy a synth oil and cheap Fram filter or something.

[zark]

The diesel oils that are rated oil for "fleet service" will have an SM or SL rating as well as the C ratings. It is a HDEO designed for both diesel and gasoline engines. The Napa 15W-40 fleet service oil is SL rated which means it has zinc and phosphorus additives. A gallon cost me $10.99.

[26th-Z]

Horrors!

I'm certain that the individual who suggested synthetic oil probably uses Crisco as after-shave! I can't believe all you guys (and there are some experts here) are making suggestions without ANY reference to what the manufacturer recommends. Whoa!

It is with distinct pleasure that Her Majesty the 26th offers this information from the engine service manual. This, of course, is from the 1970 service manual. Later issues may differ.

[EScanlon]

Chris;

The reference you present is informative and compelling.

Does this mean we should also be on the look for 95 octane gas? After all, that IS what that sheet recommends. Last I checked, 92 octane IS considered Premium, unlike the 100+ I used to pump into my motorbike in the 70's.

Don't get me wrong, it is an excellent reference and should help a lot. However, I'm just wondering how many of the oils specified are still being offered in their original specifications. That is, the ORIGINAL formula as specified by the Nissan Engineering team when that sheet was printed.

Many expendable items for our cars have changed in the 35+ years since they were new (and 40 for the dates of this specific spec sheet).

You really would have a hard time finding 175HR-14 tires at your local tire store, and if you DID find a set... would you really buy them and not Radials? Then again, would you rotate them as the original manual shows? The manual does warn about mixing the THREE different types of tires, but does NOT give a recommendation on size / type of the other two types. Does that mean we are limited to only ONE type of tire? Or that the engineers felt that you would make an educated or informed choice?

Oil also changes formulations as time goes on.

One spec sheet from my manual for the 72 Z shows that the Monograde oils from Shell and Esso listed on the sheet you provide were "Not Available" at the time of printing, and that's just 2 years AFTER your sheet. Additionally, Caltex, Castrol and BP are NOT listed, and in their place we have Sunoco alone. Not to mention that Shell's X100 oil on your sheet is now Super Motor Oil on mine (and only in Multi-Grade), and Chevron dropped the RPM in their oil name, and Texaco went to the Havoline Super Premium name.

Yet the Mil-Spec (MIL-L-2104B) remains the same for all those oils.

Hopefully that Mil-Spec is still the one that the cans you buy today, but last time I checked (about 2 minutes ago), the Mil-Spec doesn't appear on the cans...oops, plastic bottles I have.

I think part of the point of all this is, that things do in fact, CHANGE! This is what this thread is all about.

Your reference is good.... for a starting point. But as far as to what to use today... well that's what everyone is asking.

Tire sizes, types and construction.... not the same as when the car rolled off the assembly line. Same with oils, DEQ, Gasoline and so many of the other consumable items on the car. That is the nature of progress in the automotive world.

To service an older car, you ask around, from reputable sources, and from the manufacturer and even then, sometimes it boils down to a discussion of what IS available and not what you'd like it to be.

2¢

E

Edited April 6, 2010 by EScanlon