1975 Eldorado Oil Opinions

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Inline200

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Just looking for some opinions here. My cousin just bought a 1975 Eldorado Convertible in mint condition. 44k miles and he says it runs like new. I was thinking of recommending QS Defy in 10w30 or 10w40, maybe Rotella T3 15w40? What do you think would be the best choice for this engine (I believe it should be a Caddy 500). The car will be used for cruising, mostly on the weekends with some highway mixed in. Probably will be used periodically year round, just not in rain or snow.

Saw a few threads for similar engines here that went off topic, hopefully this won't go the same way. Lol
 
Rotella is also available in weights other than 15w-40. I can get it locally in a conventional 10w-30 and a semi-synthetic (T5) 10w-30.
 
What range of oil weight is specified in the owners manual?

Something like PYB should suffice.

A notch up would be Amsoil Z-ROD.

And don't forget the tranny. Find a mineral oil base DexronIII until you determine there are no leaks. It appears that you will need 5.5 quarts with a filter change.

Brake fluid and Power Steering fluid should be replaced as well. After, all, you want to be able to Steer and Stop.

Nice vehicle.
 
Last edited:
4T Motorcycle oil API (SH/SJ JASO MA) 10w40. or any 10w40. If the motor sounds like it needs more zdp throw in a bottle of B$S lawnmower sae30 or Champion vintage car oil or a racing ZDP boosting oil. Should be OK already broken in with a modern 10w40 DINO oil.
 
Originally Posted By: ARCOgraphite
4T Motorcycle oil API (SH/SJ JASO MA) 10w40. or any 10w40. If the motor sounds like it needs more zdp throw in a bottle of B$S lawnmower sae30 or Champion vintage car oil or a racing ZDP boosting oil. Should be OK already broken in with a modern 10w40 DINO oil.


It's stock. It'll run fine on any PCMO in the weight specified in the manual.
 
Originally Posted By: OVERKILL
It's stock. It'll run fine on any PCMO in the weight specified in the manual.


I haven't seen him or the car in person yet but according to online searching it appears the manual stated anything from 10w40 to even 5w30 or 5w20 as conditions arise. The 5w20 was only listed for -20 to 20 degrees and not with long highway drives. I think I may recommend the QS Defy in 10w30, since it has extra Zinc and is still SL rated.

Thanks for the ideas though. Was hoping for someone with this exact engine to come along.
 
We had a 72 Eldorado, it was poo brown and belonged originally to the late Ted Rogers, LOL! IIRC, my grandfather just used whatever oil he got on sale, which would have been Castrol GTX or Valvoline white bottle in the 10w-30 flavour. This was in the late 80's, early 90's.

The engine out-lived the car and 3x transmissions. Keep that in mind
wink.gif
 
4T Motorcycle oil = SG/SH motor oil but with better stocks and VII than in the 70s. Get ovet the picture on the bottle of a motorcycle - ITS API SH OIL !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! GEESSHHHH!
 
Originally Posted By: OVERKILL
We had a 72 Eldorado, it was poo brown and belonged originally to the late Ted Rogers, LOL! IIRC, my grandfather just used whatever oil he got on sale, which would have been Castrol GTX or Valvoline white bottle in the 10w-30 flavour. This was in the late 80's, early 90's.

The engine out-lived the car and 3x transmissions. Keep that in mind
wink.gif



Lol Big time celebrity there. Everything I've read seems to point to the engine being very well put together, especially for it's era. So it sounds like any good 10w30(especially with Zinc) will be good for all weather driving. All my knowledge of old GM V8's is with Oldsmobiles, so I'm learning as I go with this one.
 
Originally Posted By: ARCOgraphite
4T Motorcycle oil = SG/SH motor oil but with better stocks and VII than in the 70s. Get ovet the picture on the bottle of a motorcycle - ITS API SH OIL !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! GEESSHHHH!

Is this BITOG or Honda Civic forum?!
smile.gif

From valvoline today:

4-Stroke Motorcycle Oil advantages:
• High RPM, High Temperature Performance
• Wet Clutch Protection
• Maximum Horsepower
• Minimal Wear
• Advanced Cleaning
• Shear Stability
• Film Strength
• Excellent Corrosion Protection
• Meets or exceeds manufacturer’s warranty requirements
• Provides exceptional protection for ATVs
• For use in 4-Stroke Motorcycles, including Cruisers and Off-Road Motorcycles
Approvals/Performance Levels
Viscosity Grade/Other
Meets or Exceeds API SF/SG/SJ
SAE 10W-40, SAE 20W-50
Meets or Exceeds JASO MA2
SAE 10W-40, SAE 20W-50
Test
SAE 10W-40
SAE 20W-50
Vis @ 100°C (cSt)
15.2
20.0
Vis @ 40°C (cSt)
104.1
169.4
Viscosity Index
155
124
Spec Gravity @ 60°F
0.8732
0.8848
Density (lbs/gal)
7.28
7.38
Total Base No.
8
8
Flash COC (°C)
216
230
Pour Point (°C) max
-30
-24
CCS cP (°C)
6200(-250C)
8400(-150C)
MRV TP-1 cP (°C)
38000(-300C)
28000(-200C)
Noack % off @ 250°C
15.0
7.3
Sulfated Ash, wt.%
0.80
0.80
Zinc/Phosphorus, wt.%
0.112/0.103
0.112/0.103
Calcium/Sodium, wt.%
0.182/0.052
0.182/0.052
Part Numbers
Quart
740(for SAE 10W40)
Quart
743(for SAE 20W50)
 
Originally Posted By: ARCOgraphite
Originally Posted By: ARCOgraphite
4T Motorcycle oil = SG/SH motor oil but with better stocks and VII than in the 70s. Get ovet the picture on the bottle of a motorcycle - ITS API SH OIL !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! GEESSHHHH!

Is this BITOG or Honda Civic forum?!
smile.gif

From valvoline today:

4-Stroke Motorcycle Oil advantages:
• High RPM, High Temperature Performance
• Wet Clutch Protection
• Maximum Horsepower
• Minimal Wear
• Advanced Cleaning
• Shear Stability
• Film Strength
• Excellent Corrosion Protection
• Meets or exceeds manufacturer’s warranty requirements
• Provides exceptional protection for ATVs
• For use in 4-Stroke Motorcycles, including Cruisers and Off-Road Motorcycles
Approvals/Performance Levels
Viscosity Grade/Other
Meets or Exceeds API SF/SG/SJ
SAE 10W-40, SAE 20W-50
Meets or Exceeds JASO MA2
SAE 10W-40, SAE 20W-50
Test
SAE 10W-40
SAE 20W-50
Vis @ 100°C (cSt)
15.2
20.0
Vis @ 40°C (cSt)
104.1
169.4
Viscosity Index
155
124
Spec Gravity @ 60°F
0.8732
0.8848
Density (lbs/gal)
7.28
7.38
Total Base No.
8
8
Flash COC (°C)
216
230
Pour Point (°C) max
-30
-24
CCS cP (°C)
6200(-250C)
8400(-150C)
MRV TP-1 cP (°C)
38000(-300C)
28000(-200C)
Noack % off @ 250°C
15.0
7.3
Sulfated Ash, wt.%
0.80
0.80
Zinc/Phosphorus, wt.%
0.112/0.103
0.112/0.103
Calcium/Sodium, wt.%
0.182/0.052
0.182/0.052
Part Numbers
Quart
740(for SAE 10W40)
Quart
743(for SAE 20W50)


And how does ANY of that apply to a low-RPM, low valve spring pressure low-stress V8 engine???
crazy2.gif
 
This is a huge engine that makes no real power.
It's specific ouput must be close to that of a 240D.
It should therefore have no special oil requirements.
When the car was new, it almost certainly got the 10W-30 that was the all purpose oil of the time.
I don't think GM was recommending 10W-40 in 1975, although I could be wrong.
Any quality 10W-30 will take good care of this engine.
I'd worry more about the top than the engine, since it isn't a cheap thing to have to replace.
 
The last one of those motors I took apart had 90k on it and you could still read the painted on date codes on the underside of the main bearings. Very well-built engines IMO.
I'd use 10w-30 HDEO in it.
 
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