The specified GM power steering fluid is less expensive.
You are correct,
but my power steering pump moaned and squealed for a couple minutes after cold start when using GM stock PSF. According to people at Buickforums, this is a common ailment of my model year of Buick Park Ave and several other Buicks, Chevys, and GMCs of that era.
It slightly improved using Lucas PSF. It still moaned, but no squealing.
It was same with Idemitsu PSF as with Lucas PSF. Idemitsu was a side-grade from Lucas. Still moaning, but no squealing.
It improved using Lubegard Complete Multi-Vehicle Synthetic PSF, which it currently has in it. Less moaning, no squealing.
The Lubegard PSF has lower cold start viscosity than the others I've tried, and its 100KV viscosity is similar to the others.
People at Buickforums recommended I try Pentosin CHF-11 because it has an even lower cold start viscosity while still having an appropriate viscosity at 100KV.
They said I'm experiencing a bad case of a known issue with my late 90s Buick. There is 1 or 2 GM TSBs about it. They said the two known/common cures are an updated return hose and using Pentosin CHF-11 or GM cold weather PSF (even though it's not cold where I live).
I already updated the return hose, but that didn't help. Next thing to try is Pentosin CHF-11,
but they didn't tell me how much Pentosin CHF-11 I'd need to replace all fluid in system.
Based on my past experience, I think a 1 liter can might be (just barely) enough, but I'm not sure.
I could ask Buickforums how much I'd need, but it's a slow moving forum. It'd take 1-2 weeks to get an answer there.
It's so expensive. I was hoping to get away with one 1 liter can.
