Early synthetics were notorious for not being able to switch brands. The
formulations were different, causing all kinds of problems. Some early
synthetics were also supposed to shrink seals due to the formulations.
Formulations have gotten a lot better, but I still don't think it's wise to
mix two different synths together, as there are still different formulations
out there.
In a high mileage engine a good synth like Mobil 1 will loosen and remove
all the old varnish, sludge, etc, which may cause a darkening of the oil
until it's all cleaned out of the engine. On really high mileage engines,
changing to a synth may actually cause oil leaks and burning, due to the
fact that all the sludge & varnish is removed from seals that are so old
they can't expand to seal the gaps anymore. It seems you don't have that
problem.
You may be seeing some effects from the removal of varnish, sludge, etc from
the dino oil (Mobil 1 is supposedly better at cleaning this stuff out than
other synths). Even after all the dino, sludge, and varnish works it's way
out, the oil will still probably go from a light honey color to something
honey-brown over the course of 3000 miles.
on 3/25/01 11:58 AM, Ronald Wong at ron-wong@home.com wrote:
> Synthetic oils should get lighter and lighter as you go through changes and
> all the dino stuff gets flushed out. Based on Patrick Engram's comments I
> wouldn't mix the two. I'm beginning to think there's some sort of reaction
> going on here.
>
> Ron
> 00 PB SLT QC 4X2 5.9 46RE 3.92 LSD
> For modifications see my DML Profile (URL follows)
> http://www.twistedbits.net/WWWProfile/dakota/Kw9pV1EkFeOYY
>
>
> -----Original Message-----
> From: owner-dakota-truck@buffnet.net
> [mailto:owner-dakota-truck@buffnet.net]On Behalf Of Chris Spotts
> Sent: Sunday, March 25, 2001 8:49 AM
> To: DML list
> Subject: DML: Dark Oil?
>
>
> Ok guys (and girls), here's another question about oil. I switched over to
> synthetics 2 oil changes ago (about 39000 miles on the odo). The first time
> I used castrol syntec and the second time I used mobile 1 (plus the good
> purolator filter). My question to you guys is: should the oil become
> gradually darker and darker as I drive? I have about 2000 miles on the
> truck since the last oil change and the oil is noticeably darker. I never
> have to add any oil and it's always the same level on the dipstick. Should
> I worry that the oil is getting so dark? Or is it just because I waited so
> long to change it that the synthetic is still mixing with the old dino
> stuff?
> One more question: can I mix oils? I have 2 qts of castrol syntec 10w30
> and 2 quarts of mobile 1 5w30. Anyone think I can make some "castrol 1"
> 7.5w/30?
>
> -Chris
>
> ps- sorry for such a long post on such a boring topic
>
>
This archive was generated by hypermail 2b29 : Fri Jun 20 2003 - 12:00:27 EDT