Amsoil 15w-40 vs. 20W-50 Opinions Wanted (long)

mdv

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531
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MA
I'm currently using their 15W-40 in a 1990 BMW 325 that is a daily driver but also sees use on a roadcourses under some pretty harsh conditions. With ambient temps. in the 70's, on a roadcourse my oil temp. gets up to 220 and the pressure goes no higher than 50 psi. On the street, I usually see temps of 180 and pressure of around 65 psi maximum at startup and then rpm dependent after that. What I'm wondering is whether or not I should use the Series 2000 20W-50 in this car now, as I expect the ambient temps to be in the 90's for a while. I believe this will help the oil pressure be more stable when running hard, but won't this also cause the oil temp. to be hotter as well? I'm looking for other thoughts on which oil to go with all things considered, as this car has a bypass system on it and I don't want to change the oil frequently. I'd rather find one and use it for a long time. Thanks. [ June 04, 2003, 10:18 PM: Message edited by: mdv ]
 

MolaKule

Staff member
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Iowegia - USA
I would stay with the 15W40 and opt for oil flow rather than pressure. The 20W50 may well cause increased pressure but will it flow as fast and cool as quickly?
 

mdv

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MA
quote:
Originally posted by MolaKule: The 20W50 may well cause increased pressure but will it flow as fast and cool as quickly?
Thanks for the input. The 15W-40 does cool down very fast. During the cool down lap, the oil temp would drop to between 200-210. What amazes me is that after parking the car and leaving for 20 minutes, the oil temp registers 150 or so. It cools down much faster than I figured it would.
 
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Northeast US
[Off Topic!] 90 degrees ambient? I wish and I hope. Mass is stuck in post springtime rain and clouds - I think it's gonna be one of those summers up here. It seems as if New England has been moved back to 'ole' England right now. Good luck with the Amsoil.
 
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Dixie
mdv, I have had excellent results in older Beemers with the Series 2000 racing oil. I would run that for six months out of the year and run the Amsoil 10w-40 during the colder months. The Series 2000 has very effective friction modifiers and will generate extremely low wear rates in this engine. TooSlick
 
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East of IGO
Why don't you try 10w/40 redline and see what happens. 20w/50 syn would work fine . and help up the pressure when the oil gets to operating temps . Keep us informed on what you do and how it works out.
 
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47,718
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Duvall WA - Pacific NW USA
All I can write is the Amsoil Series 2000 20W-50 has been in my turbo Volvo, winter and all for 30K miles/3 years or so (changes at 10K). This oil to me is the real thing and is well suited to many BMW engines as well. The 15W-40 is a great oil as well but I think the 20W-50 will surprise you. Look at the specs on paper, too.
 

mdv

Thread starter
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531
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MA
quote:
Originally posted by diesel_fan: [Off Topic!] 90 degrees ambient? I wish and I hope. Mass is stuck in post springtime rain and clouds - I think it's gonna be one of those summers up here. It seems as if New England has been moved back to 'ole' England right now. Good luck with the Amsoil.
I hear you, lately it's been miserable. I do think the warm weather is coming and I remember a few times last year where we were very close to 100 with the track temp. at 125 or so.
 

mdv

Thread starter
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531
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MA
Here's how I see things so far: Amsoil 15W-40: Pros- Beter startup protection and more rust inhibitors while the car is parked for extended periods. Better flow under higher temp conditions to carry heat away. Con- HT/HS numbers slightly lower (is this a consideration at 7000 rpm with only 50psi of pressure). Amsoil 20W-50: Pros- Very shear stable, friction modified, made for abuse, and lower volatility. Cons- Very thick at startup and won't flow as well. Will run probably run at a higher oil temp (how much hotter and isn't 220 pretty high already?) One other question: If I switch to the 20W-50, should I replace the bypass and FF filter so the two oils don't mix, or should I not worry about it? Thanks.
 
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2,480
If you're not having consumption issues...why not stick with the 15-40? Sounds like it's working fine...then again, you could try it and always go back if not happy with the results.
 
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N. VA
mdv, I've got a LTW pan and cooler on the ti S50 (M3 swap for everyone else) and drive it fairly hard and autox, track to come. It had M1 15W-50 and now Amsoil ARO 20W-50, cold/hot idle 50/20 psi, cold/hot 3k+ 60/50 psi for both oils. I'm going to try 0W-30 in the winter just for cold startup. My newer motor is supposed to be tighter for those 5W-30 specs, your older one should be able to use the 20W-50 fine. I would say don't worry about the temp but it should help keep the psi up. Weights will mix fine.
 

mdv

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531
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MA
Gary: That car must scream around! Thanks for everyone's input. I think I'm going to try the 20W-50. Pablo's results look very impressive and I have this feeling that if I don't at least try the oil I'll drive myself nuts wondering which is better.
 
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74
Location
N. VA
I've also never seen a temp above 200*F yet, moving is 160-70, sitting 180-200, after constant 4000 rpm cruising. But the oil is dang hot when changed, I've got to check where the sender is mounted. [ June 06, 2003, 06:37 PM: Message edited by: Gary ]
 
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Dixie
MDV, I overlooked the fact that you have a bypass filter and want to run the same oil year round. A 20w-50 would be a bit too thick in Mass in the wintertime. I'd stick with the 15w-40 or the Amsoil 10w-40 for year round use. TooSlick
 

mdv

Thread starter
Messages
531
Location
MA
quote:
Originally posted by TooSlick: MDV, I overlooked the fact that you have a bypass filter and want to run the same oil year round. A 20w-50 would be a bit too thick in Mass in the wintertime. I'd stick with the 15w-40 or the Amsoil 10w-40 for year round use. TooSlick
Thanks for clarifying that on the 20W-50. I'm still deciding if I'm going to drive the car this winter or store it, so the 20W-50 may still be an option.
 
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