question for the oil guys

[Rekoob]

i have a simple question about oil on my '78 sc. but im sure the answer is much more complicated

what would be the best oil i could and should put in this car where i DO NOT know the history?.
i don't know what was used in the past (full syn, part, reg)
im not a hard driver on the car, and it will be drivin mostly up in BC, canada (summers only)
i like to find a good oil and always stick with it, but i know different, and older vehicles can be picky with drastic oil changes.

oh... i have 174000 miles with one rebuild some years ago..

thanks for the help.

[redstrosekNic]

I'm no oil guy, but you can't go wrong with Shell Rotella (15W40) or Valvoline VR1 (20w50). Not knowing any history, I would change the oil, then change it again within a few months to be sure you get all the old stuff out. I choose the Rotella because it is a quality oil, and is one of the most affordable options for a car holding a lot of oil.

[boxster03]

Please allow me

[Jack Stands]

It seems that oil recommendations are like rectums, everyone seems to have one! I agree that it's best to choose your poison and stick with it. Changing the oil and filter at regular intervals is probably the most important thing to do. I think that any of the oils with enough ZDDP additive should work well, and staying with the major brands will give you an oil that you can reliably continue to source in the future.

[S2GART]

I use Shell Rotella 15W-40 as well. It's readily available, comes in 1 gallon jugs and quarts. Since the SC takes 10.75 quarts, you just need 2 jugs and 3 qts. Also at least on my '83, Shell oil was the factory fill.

[HarryD]

20W-50 Brad Penn or Valvoline VR-1 (Dino) are be my selections. If I wanted a15W-40, I would go with Rotella or SWEPCO.

[darrin]

The OP raises an issue that's outside of the normal "what's the best oil" post and that I don't recall seeing addressed before (though I've not read more than a few pages of the "best oil" threads) -- would introducing synthetic into a car with older oil lines/seals/etc. that had only "seen" conventional dyno oil encourage the development of oil leaks, etc.

When I originally got my car in the 90s, I recall being told that conventional oil caused parts of the lubrication system to expand and that switching to synthetic could cause these parts to contract and leak oil. This caused me to stick with dyno until I had my engine rebuild, at which point I switched to synthetic.

Is there any disadvantage to using synthetic oil in a car that always used dyno (or, conversely dyno in a car that always used syn)?

[Arne2]

Originally Posted by HarryD

20W-50 Brad Penn or Valvoline VR-1 (Dino) are be my selections. If I wanted a15W-40, I would go with Rotella or SWEPCO.

Brad Penn is also available in 15W-40...

[schumicat]

That one has been beaten to death also. Depending on who you ask the answer is yes or no.

Originally Posted by darrin

The OP raises an issue that's outside of the normal "what's the best oil" post and that I don't recall seeing addressed before (though I've not read more than a few pages of the "best oil" threads) -- would introducing synthetic into a car with older oil lines/seals/etc. that had only "seen" conventional dyno oil encourage the development of oil leaks, etc.

When I originally got my car in the 90s, I recall being told that conventional oil caused parts of the lubrication system to expand and that switching to synthetic could cause these parts to contract and leak oil. This caused me to stick with dyno until I had my engine rebuild, at which point I switched to synthetic.

Is there any disadvantage to using synthetic oil in a car that always used dyno (or, conversely dyno in a car that always used syn)?

[Dodge Man]

SHORT ANSWER: Just get the level of ZDDP necessary in whatever brand you like and adjust the viscosity to your climate.

I use VR-1 because I got a sweet deal and I happen to like Valvoline like a lot of my serious racer buddies. VR-1 is racing oil so you have to be militant on the oil change intervals. Valvoline Nitro 70 was also a favorite with the local bikers(Harleys & Indians) back in the day. Nitro 70 would also keep my old 57 Chevy from smoking out of the road draft tube which was very important when trunk sneaking people into the drive-in(outdoor) back in the day. To make it simple, it is not the oil or the brand but the additive package. Time to watch the oil brand loyalty posts boil over!!! Right now, I am feeling Joe Bob thru my psychic medium for some reason.

[Ronnie's.930]

You don't mention a concern with cost, so in light of that, the best oil to use is Motul 300V 4T (15w50).

[Nick Triesch]

Glory be to the Brad Penn, The Valvoline VR1 and the holy Deep purple, amen.

[HarryD]

Originally Posted by darrin

The OP raises an issue that's outside of the normal "what's the best oil" post and that I don't recall seeing addressed before (though I've not read more than a few pages of the "best oil" threads) -- would introducing synthetic into a car with older oil lines/seals/etc. that had only "seen" conventional dyno oil encourage the development of oil leaks, etc.

When I originally got my car in the 90s, I recall being told that conventional oil caused parts of the lubrication system to expand and that switching to synthetic could cause these parts to contract and leak oil. This caused me to stick with dyno until I had my engine rebuild, at which point I switched to synthetic.

Is there any disadvantage to using synthetic oil in a car that always used dyno (or, conversely dyno in a car that always used syn)?

No really. If you want to try one, why not.

When synthetic oils were first introduced, they lacked an additive that caused some types of rubber seals to swell like the Dino oils. As a result, there were numerous reports of excessive oil leaking when you switched from a dino to syn oil. Since that time, the oil makers wised up and added something to the syn oils swell the seals. At this time you "should" be able to switch back in forth but as in all things YMMV.

[HarryD]

Originally Posted by nick triesch

glory be to the

holy trinity

brad penn, the valvoline vr1 and the holy deep purple, amen.

[darrin]

Originally Posted by HarryD

No really. If you want to try one, why not.

When synthetic oils were first introduced, they lacked an additive that caused some types of rubber seals to swell like the Dino oils. As a result, there were numerous reports of excessive oil leaking when you switched from a dino to syn oil. Since that time, the oil makers wised up and added something to the syn oils swell the seals. At this time you "should" be able to switch back in forth but as in all things YMMV.

Thanks Harry!

[Rekoob]

well i do apologize for reposts, im still learning this forum and now realise to benefits of the search.
however, trouble is finding someone with the same set of circumstances or in the same situation.

seccondly, considering the age of these cars and this, as well ass alike forums, the same questions are sure to be asked over n over as newbs enter the scene and want a more specific answer to their problems or the fact that everyday there are new answers to these questions and a little freshen up never hurt anyone.

Valvoline Nitro 70 was also a favorite with the local bikers(Harleys & Indians) back in the day

would this mean its safe to use a 20w50 motorcycle oil? say redline, castroll, or mobil one? i do have access to these for a good price, and if its fine to use, why not take advantage!?

Not knowing any history, I would change the oil, then change it again within a few months to be sure you get all the old stuff out.

i do know the oil was changed on time and the car was (overall) very well taken care of. it was my fathers car, trouble is we don't speak, he's not a "mechanical" guy and when i was younger i never payed too much attention to those details. so its easier to act as if i know nothing when asking questions.

You don't mention a concern with cost, so in light of that, the best oil to use is Motul 300V 4T (15w50).

im by no means rich or wasteful, however, i will spend the money on something i know is well worth it.

also what would be a "regular" oil change interval for the average "weekend cruiser" same as regular cars? i remember hearing its a bit longer but i have no idea to be honest. ive always done my cars, bikes ect.. well before the interval but thats just me. at 11 quarts each time, these oil changes may need to wait a little closer to their due date.

thanks for all the advice! its very much appreciated.

[HarryD]

No need to apologize for being a noob. there is a ton of info here and it can be hard to separate the food stuff from the bad stuff.

Many of us change oil and filter (use a Mahle one) every 3-5000 miles.

If you can get Mobil 1 v-twin at decent price it may be worth while as I hear it has the right amount of the"good stuff".

This is an excellent article and the author posts here as well. Oils: What motor oil should I use? Which oil is best for my Porsche or aircooled engine?

[Ronnie's.930]

Rekoob - the reason for the "not this sh#t again", and other jokes, is that oil is always a hot topic on this forum and most of the debates lead to absolutely nothing - what one guy says is liquid gold the next says is liquid feces. For example, Brad Penn is often praised on this forum, but in the turbo forum, it is considered garbage as it cokes very readily in the turbo bearing cartridge and the particles end up throughout the oiling system (including plugging the cam spray bars).

The same goes with oil change intervals - as many people that say "every 3K or you're and idiot" will tell you to follow the factory recommendations.

[A horse with no name]

For what it is worth, my 2 cents; I use Mobil 1 15-50 synthetic, which for the miles I put on between late spring and early autumn is really not necessary.

FYI - $25.00 for a 5 quart jug at the Walmart in Bellingham Wa

(No leaks with synthetic at 120,000 km ->75 K miles )

.

Originally Posted by Rekoob

i have a simple question about oil on my '78 sc. but im sure the answer is much more complicated

what would be the best oil i could and should put in this car where i DO NOT know the history?.
i don't know what was used in the past (full syn, part, reg)
im not a hard driver on the car, and it will be drivin mostly up in BC, canada (summers only)
i like to find a good oil and always stick with it, but i know different, and older vehicles can be picky with drastic oil changes.

oh... i have 174000 miles with one rebuild some years ago..

thanks for the help.

[SilberUrS6]

My answer?

Yes, you should use oil.

You're welcome.