Most agree multigrades are just fine for almost all jobs but what about hot weather use with no cold starts on a hot small block or big block such as a 350/383 stroker, 383 Dodge, 454, 440 or 426? Should one jump right up to a 40 or 20W50 weight or would a group 4 SAE 30 (AMSOIL diesel sae30) be ok for most non drag race conditions? Also what weight of oil was used in the 60's and early 70's in such motors in cars and trucks?
SAE30 or XW30?
- Thread starter hk33ka1
- Start date
- Status
I can't answer the history part - I want to know, too!! Especially in equivalent to today's viscosities - back then it was API SC, SD, SE....but viscosities....hmmm....
I would say good synthetic 20W-50 would be good in any of those motors. I would never run a straight petroleum 20W-50.
If I had a real alky or nitro loose piston blower monster I would use a straight synthetic 60W.
I would say good synthetic 20W-50 would be good in any of those motors. I would never run a straight petroleum 20W-50.
If I had a real alky or nitro loose piston blower monster I would use a straight synthetic 60W.
Yeah I have run Xw50 synthetic in a stock 350 in my truck and was happy with it. I am using ATM 10W30 now and am going to go for a year with 6 month filter change, and do several analysis. Just wondering if SAE 30 AMSOIL or any brand for that matter might hold up better than a multigrade (yes I know the VII's are much better these days) in the most extreme and even regular use. Extended drains are not an issue for me with toys and these engines. Also who remembers when we (North America) started primarily using multi grades in gas and diesels? Almost everybody now uses 5/10w30 and 15w40. When did this become commonplace? Instead of 30 in the summer 10 in the winter. What did they use in the old diesels? HD 30 or 40?
BTW Pablo no worries of me using a straight petroleum anything, I am one of those Amsoil nuts now
BTW Pablo no worries of me using a straight petroleum anything, I am one of those Amsoil nuts now
Patman
Staff member
I see no need for straight weight oils anymore, even in hot climates. You'll still get a lot more protection from a 10w30 than you would from a straight 30, even if the engine is only started when it's 80-100F outside.
- Joined
- Jun 2, 2002
- Messages
- 4,198
I remember reading not too long ago about a test that was conducted by Mercedes-Benz at the University of Oslo in Norway. It was a specific wear test conducted on a random use engine (2 cylinder, 4 cycle, gasoline powered generator) using a multiviscosity 10W-30 and 20W-40 oil and a straight weight 30. These were all mineral oils and the manufacturer of the oil was not mentioned. Their conclusions were very surprising. The 10W-30 oil showed hideous amounts of wear and was deemed completely unacceptable by their standards. The 20W40 was acceptable but still showed much more wear than the straight 30 weight. Their conclusion was; engines that were not started and used on a regular basis would benefit from the straight 30 weight oil as opposed to the lighter multi-grades.
I concluded that this would represent a engine such as a lawn mower or snow blower that gets started once a week and is run for maybe 1 hour and then gets put away.
I wish I had saved the article. It was interesting. I'll try to find it and post it if I can.
I concluded that this would represent a engine such as a lawn mower or snow blower that gets started once a week and is run for maybe 1 hour and then gets put away.
I wish I had saved the article. It was interesting. I'll try to find it and post it if I can.
hk33ka1 - What vintage are those monster engines? The reason I ask is that a few years ago I helped my father-in-law rebuild the 312 V-8 in his '56 T Bird. We installed new seals, parts, etc. I made an error in judgement by recommending he use a 15W-50 synthetic oil. Within about the first 1,200 miles the rear main seal began to leak quite bad. It didn't dawn on me at the time, but evidently the rope-type rear main seal and synthetic oil weren't capatible.
He's since switched to a good 15W-40 CH4-SL conventional oil. Most of the rear main oil leaking has subsided. The point I'm making is that possibly an older motor's seals (old or replacement seals) may not be capatible with any viscosity synthetic oil.
DITTO THAT !!
I think if you want the added protection for engines running high oil temps, go with something like M1 15W-50 or some XW-40 oils. Synthetic may be the best choice for high heat stress. I would not use straight weights anymore
I think if you want the added protection for engines running high oil temps, go with something like M1 15W-50 or some XW-40 oils. Synthetic may be the best choice for high heat stress. I would not use straight weights anymore
Yeahh those rope seals ...they are guaranteed to leak no matter what you do. Enjoy while they are not because they will start soon....we once tried to seal the front cover on a 1951 Oldsmobile with a rocket V8 ...lasted for about 5,000 miles and they were weeping again..........they were common on some engines even into the 60s......Some synthetic oil manufacturers (I believe even M1) even warn using synthetics in engines with any cork gaskets. There are excellent dino oils out there. just use them and shorten the oil change interval and you'll be fine....
[ January 04, 2003, 10:49 AM: Message edited by: Alex D ]
quote:
Originally posted by M Smith:
hk33ka1 - What vintage are those monster engines? The reason I ask is that a few years ago I helped my father-in-law rebuild the 312 V-8 in his '56 T Bird. We installed new seals, parts, etc. I made an error in judgement by recommending he use a 15W-50 synthetic oil. Within about the first 1,200 miles the rear main seal began to leak quite bad. It didn't dawn on me at the time, but evidently the rope-type rear main seal and synthetic oil weren't capatible.He's since switched to a good 15W-40 CH4-SL conventional oil. Most of the rear main oil leaking has subsided. The point I'm making is that possibly an older motor's seals (old or replacement seals) may not be capatible with any viscosity synthetic oil.
[ January 04, 2003, 10:49 AM: Message edited by: Alex D ]
For tough conditions: high power output race engines, desert type hot weather conditions, etc., mono-grade is the way to go.
The only time you do not want mono-grade is in extreme cold conditions. When your breath is starting to cause icicles to form on your nose, use the VI-packed multigrades: 0W-30, 5W-30, etc.
Use of multigrade in other than moderately cold to very cold conditions may cause, as the other poster said, "horrendous...wear."
The only time you do not want mono-grade is in extreme cold conditions. When your breath is starting to cause icicles to form on your nose, use the VI-packed multigrades: 0W-30, 5W-30, etc.
Use of multigrade in other than moderately cold to very cold conditions may cause, as the other poster said, "horrendous...wear."
This is nonsense. Take a look at all the UOAs of multigrade oils listed in this forum and you won't find any that back up your statement. At any ambient temp under 100*F, an Xw30 oil will be thinner than a straight 30, hence it will pump more easily and get to all the critical parts (like OHC, lifters, etc) faster than a 30wt. Since virtually all engine wear occurs at start up, a multigrade oil will provide more wear protection than a straight grade under just about any condition, especially if it's a synthetic.
With the exception of Briggs and Stratton, I don't know of another engine manufacturer in the last thirty years (since the original Beetle bit the big one) that's recommended straight weight oil.
My manual (1989) lists SAE 20, 30 and 40 as acceptable. However much lower range of operation and SAE 20 is not acceptable for high speed driving. I would have to check to tell exact.
[ January 21, 2003, 12:13 PM: Message edited by: Jason Troxell ]
[ January 21, 2003, 12:13 PM: Message edited by: Jason Troxell ]
JonS, as luck would have it, recently the good people at Castrol mailed me their latest Typical Inspection Data sheets. I can answer your question now, thanks to them.
Castrol HD-30. Viscosity cSt 100 C: 11.5.
viscosity cSt 40 C: 97
Castrol 10W-30. Viscosity cSt 100 C: 10.7.
viscosity cSt 40 C: 72
I believe the data shows HD-30 has it all over GTX 10W-30 in terms of extended-period high temperature performance.
Before the widespread use of liquid cooled engines, when engine blocks had fins, HD-30 was the one for high temperature operation. Sometimes people even used HD-40 in July/August. But HD-40, that is another story. ***smiles***
For GTX 5w-30: LOw temperature(Centigrade) cranking viscosity, cP max: less than 6600(-30C)
Low temperature(Centigrade)pumping viscosity, cP max: 60,000(-35C)
Viscosity Index: 160
Pour point(Centigrade): -33
- Status
Similar threads
