Hello folks

It's been a long time since my last post.

I have a 72 350 with 75k original miles, running smooth.

It's time for an oil change, I have some cans on my shelf.

Synt
Mobil1 15w-50
Mobil1 0w-40
Amsoil 10w-40
Chevron 15w-40 (now running on that)

Joe Gibbs XP5 Semi-Synth

Which one would you choose?

thanks

 

I drives on mobile 0w-40. But that is manely to have "good cold starts" during the winter here in norway. (i does not drive the care during the winter, but start it up once a mont)

 

I use Rotella T 15W40. Engine builders have recommended that oil to me due to it's zinc content. Especially for flat tapped cams, Rotella T is perfect! I believe that this oil can only be used in vehicles without cats..

 

rotella T diesel oil, wix filter, others dont have enough wear protection for older engines. i look for the api approved, thats the ones i dont use due to reduced zddp, for emissions.

 

Check this out, it's supposed to be the best thing for our older engines. WB

http://www.valvoline.com/pages/produ...asp?product=50

 

 

I have used valvoline 10w-40 in my 69 350 that was bored and stroked to a 383 in 94 and it still runs as good today as it did in 94.
in my opinion the heavier 20-50 oils are to thick and can let damage happen on cold start ups before oil is circulating unless you are using the engine for racing purposes.

 

Of the ones you have listed, which I think is the actual question, I'd go with the Mobil1 0w40.

 

Yes, I'd like to choose from the oils I already have in my garage.

I Use Mobil1 0w-40 in my SRT-10, which I also seldom drive in winter so "0" is the right choice. I would go 15w-50 since I only drive my Vette during Summer, so "50" would help at high temps.

 

I think 50w is 'overkill', even at 100F (???C). It will just make your pump work harder. Mobil 1 10W40 would be my choice.

 

What is "zddp" and why do we want it in our engine oil ??? I rebuilt my motor to L79 specs back in 1989 and broke in the cam and motor with Castrol 10W-40. After the first 4000 miles (or so) I switched to Mobil-1 Fully Syn 15W50. Motor has about 15K miles on it now and haven't really seen any problems (oil wise).

 

Pssst! Everyone's all worked-up about having enough zinc in motor oil. I believe it has to do with trying to make solid lifters live with excessive valve lifts and super-duty spring set-ups. [I thought that's why roller lifters were developed.]

 

I'd chose the AMSOIL 10w40... but, maybe I'm biased.

Seriously, in answer to a few comments above, ZDDP, or Zinc dialkyl dithio phosphate, is an anti-wear addditive in oils. The relatively new API SM/ILSAC GF-4 specification for 30 grade automotive oils limits phosphorus to 0.08%, or 800 ppm to help protect the catalytic converters in new cars.


Many people turn to diesel oils, but unfortunately, the new API CJ-4 specification also puts limits on phosphorus in diesel oils, but at a higher 1200 ppm limit (so better than API SM automotive oils). Shell Rotella T is now CJ-4 and will have this limit.

There are some oils on the market that have higher levels of ZDDP, including one of the original posters choices.

AMSOIL makes these oils which all have zinc on the order of 1275 ppm, and phosphorus on the order of 1365 ppm.
AMSOIL Series 2000 20w50
AMSOIL SAE Synthetic High Performance 20w50
AMSOIL SAE Synthetic High Performance 10w40
AMSOIL Series 3000 Synthetic 5w30 Heavy Duty Diesel Oil

Mobil 1 also recently added this table to their website providing some good data on ZDDP levels in their oils:
http://www.mobiloil.com/USA-English/...duct_Guide.pdf

 

I would not use synthetic oil in an engine that was built with tolerances that did not take into consideration synthetic oil. Thirty five years ago, synthetic oil was not on the shelf. It's very thin compared to the the dino oil the engine was built for.

You may find that your seals can't contain the synthetic oil.

WalMart has oil that is formulated to the old SF standard for cars built prior to 1987. That's what I will be using from now on in my 454.

Not because I don't think synthetic oil has superior properties but because the SF oil was made for old engines and the synthetic oil was made for new engines. Different formulations to meet different objectives under totally different circumstances.

cc

 

As i concluded the information from mobile 1 internet site, the 0w - 40 had a 1000ppm of zinc. i think this is quite high, as the one i could find (of mobile1) that had the highest was the 5w-40 delvac oil witch had 1200 (that oil was intended for diesel truck and machinery.

Been a while since i checked this, so i might be wort looking at their site to doubble check if the zinc is what is impotrant to you.

 

so according to this, Joe Gibbs would be the best since it's specific for old engines with high tolerances.

thanks everybody for the hints.

 

Ciao

I'd use:

Mobil 15/50 or
Motul comp 10/60
Castrol 10/60 RS (or 'edge' as it has been renamed now)

Motul is pretty good for heavy duty drivers

 

Synthetic oil isn't necessarily any "thinner" than conventional oils. Oil manufacturers test and report their oils viscosities at 40C (100F) and 100C (212F).

Mobil 1 5w30 has a cSt viscosity of 64.8 at 100F and 11.3 at 212F according to Mobil 1's website. By comparison, Valvoline conventional 5w30 has a viscosity of 63.0 at 100F and 10.78 at 212F according to Valvoline's website. The synthetic Mobil 1 has a higher viscosity than does the conventional Valvoline. So, which is "thinner"?

There are many myths circulating regarding synthetic oils and seal leakage. Due to the significant variation in synthetic oil base stock, blanket statements about synthetic oils and seal leakage may be inappropriate. Many synthetics have a highly processed petroleum basestock (Group III). Others such as AMSOIL and Mobil 1 have a PAO basestock (Group IV), which tends to shrink seals. And yet others, such as Red Line use an ester basestock (Group V) which tends to swell seals.

Most synthetics contain higher levels of detergents, which will clean sludge from seals exposing them to oil. Companies such as AMSOIL add a small percentage of Group V ester basestock to their oils to counteract the impact of seal shrinkage caused by the PAO basestock. The result is a fluid that will actually slightly swell seals (on the order of a few percent). But, if the seals are dried and cracked and the higher levels of detergents in the synthetic cleans the sludge exposing these dried and cracked seals to oil, it will likely leak. For those that have never used synthetic and may have really old seals, you might want to stay away from synthetics. For others, who kept their oil clean and prevented sludge buildup, synthetics shouldn't negatively impact your seals.