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Synthetic oil question

3130 Views 29 Replies 19 Participants Last post by  coho761
I went to Mobil 1 advanced formula synthetic oil 5K ago...My question is this oil is said to be good up to 15K but my oil is getting dark is this normal :confused: Because using reg oil)(Castrol) at the 3-4k normal change my oil looked almost as good as when I put it in...Would you suggest a changing of my oil filter(mobil 1) before my next synthetic oil change is due or are oil filters suppose to last as long as the oil :confused: 50k on my car ...Thanks...~Radd Guy~
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i dont trust that stuff at all i'd say stick to normal 3k oil specially if you run your engine pretty hard
Everyone has their opinions on this subject but most will probably tell you to change the mobil 1 at 3 to 5k just like dino. Many just believe it's better oil but it still gets just as dirty. Personally I stick with dino and have 237k on my '92 Camry, 60k on my '01 Camry and 200k on my '91 Toy truck. But I certainly won't argue that synthetics aren't better as long as you change it like you would dino.
to me it comes down to when oil gets dirty change it whether dino or synth when i use a new brand of oil i look at it every 1000km when it gets black time to change. right now using Castrol GTX and getting 5k which is fine.
It's hard to say if the oil is still good or not without analysing the oil.

Check out this forum. You will find lots of information about oils.
Its not about synthetic oil being cleaner. Its about keeping its viscosity longer. Dino oil loses its viscosity at around 3000mi. On the other hand, synthetic stays viscous until anywhere from 5000 to 15000 depending on which oil you get. Personally, I use Mobil 1 and change it out every 5000. If your oil isn't getting dirty, then its not doing its job. All the dirt and grime thats in the engine that the oil is supposed to take off stays there.
^ Your Mobil 1 synthetic can probably go longer than 5000 miles. I'm running Mobil Clean 7500 for 5000 miles. Reports on the forum I mentioned above shows good results after 5000 miles with Mobil Clean 7500. Then again, almost all dino oils you get now can go 5000 miles no problem.
True, I can probably change it at 10,000 and be ok. The only reason I change it at 5000 is (1) to stay on the safe side; its never too early to change your oil.. and (2) for the sheer joy of working on the car. :lol: 10k is a long time to wait... :lol:
Its normal for synthetic to look dirty pretty fast but that doesnt mean its not doing its job,in fact that means it is.I am also using the 15k Mobil one and wont change it until at least 10k.The only thing i am wondering about is should i change my K&N oil filter before the 10K is up.I probably will.
I am also using the 15k Mobil one and wont change it until at least 10k.The only thing i am wondering about is should i change my K&N oil filter before the 10K is up.I probably will
That's what I was wondering if a filter is built to last longer then the 3K that you would normally change your dino at :confused: ...I would think that if you didn't change it by 8-10K your filter would be close to solid sludge and just be bypassing :yikes: This girl I knew didn't know what a oil change was and must have went 15k with dino, when I changed the oil/filter for her it must have weighed 5 lbs:lol: ...I wonder if they make special filters for synthetics or maybe they should:clap:...~Radd Guy~

:preach: If Barbie is so popular, why do you have to buy her friends? :preach:
When you switch from dino oil to mobil1, your first 2-3 oil changes will be darker than usual (this was my personal exp as well). Pursuant to which the oil will be golden at times when you do you you are correct, the oil when switched from dino to synthetic will be dark...this is normal. But i wouldn't go as far as 15K with that. 5K-7K at the most to be on the safe side.
If going with synthetic and extending oil change to 10,000 miles, I probably would change the filter half way through even if it was Mobil 1 or K&N filter. I use oversized filter on my Camry because I extended my oil change interval. I use the slightly longer filter that the Gen 5 Camry uses.
Regular Mobil 1 and 10K with filters at 10K also. Dirty 'looking' oil often meets additive and viscosity specs when sampled. Mobil factory reps have told me they use oil sampling to go 20K with most of it highway. I go 10K just to be safe.
'94 w/ 235K.
52 year old truck, refrigeration & industrial mechanic here. I work for a nationwide fleet which we have done oil samples for many years. Most diesel engines use to require 10k mile oil changes using dino oil. Over the years, this has increased to 20k. Anything below that would be waisting oil. Cummins has a new system that extends oil changes to half million miles! Transmissions and diffs use to be 90w dino. It's all 50w synethic and never has to be changed. I have a bunch of friends who are into stock car racing and they swear by Mobil 1 for their whole drive train. Industrial motor gear drives last forever using synethic and break down often if using dino oil. Pennzoil & Quaker State are the 2 biggest creators of sludge in a motor. Ask a engine rebuilder sometime. Synethic doesn't create sludge like dino. You can tear down a engine that has run synethic for 200-300k and the interior is clean. Most of the posts on this thread is myth. Synethics run the same if not more additives than the dino and you can switch over at any time without worry of seals leaking etc. There's many websites on the subject but countless forums spreading the myths.

I had a 87 Mazda B2000 company pickup truck where the engine finally blew at 310k miles. I ran 15-40 diesel oil (Mobil Delvac) and never had a ounce of the required 10w30. I had the long block rebuilt and the engine rebuilder said Mazda's are usually boat anchors and don't last that long, compared to Toyota, etc. He said to keep running 15-40. Plus I rarely changed the oil under 10k, only did it when I felt like it.

In my Corolla I run Mobil 1 Extended Life and change oil at 15k and using Wix or Napa Gold (same) filters. Oil filters is another subject all together. Not all are created equal. Fram is by far the worse which uses a cardboard anti-drain back valve. Wix, Mobil 1 and others are on top. I do recall years ago while using Fram filters that when starting the cold engines, you'd hear valve tappet noise because all the oil drained out of the filter. You get what you pay for in filters. There's many websites on the subject. I don't run Mobil 1 to save money or extend my engine life. I use it because my Toyota is a commuter car that gets 100+ miles daily and I save on my own labor time. I hate twisting wrenches on my own time. Our Toyota's will last well over 300k if taken care of properly, usually done by controlling your right foot.

So you guys keep supporting all those terrorist countries by buying their oil and changing it out at 3k. You're just throwing your money away.

Here's an interesting website:
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Fram=junk, always come in last in every filter test but their own.
I haven't gone as far as 15K, as the oil just had become too nasty after about 6K, but usually synthetics will go about twice as long as the dino oil, cost about twice as much also.
Amsoil 25K protection :confused: .....Any local American stores sell this cause I've never seen it sold in walmart :eek: Hows their filters rate :confused: ....Radd Guy
Evil Corolla S said:
not to hijack the thread but i have a synthetic oil question thats been on my mind. Does syn oil warm up quicker in the winter than regular dino? that would be a major factor in me switching oil type.
No! (speaking from one car of mine using dino and one car using synthetic).
I plan on switching to either Mobile 1 or Amsoil soon. I am using supertech oil filters from walmar right now because I am auto-rx ing my toys to get the sludge out. After I that I will probably switch to Puralaltor oil filters. They are made by Champ, which makes the best oil filters for a number of companies.

Raddman, do a goole search on amsoil in your area, they are only sold by small local dealers, that's what makes it a pain in the ass, IMO. But they appear to be better than Mobile 1 in tests.
even if you drive hard, 10k out of mobil1 synthetic is still good. Don't worry about it looking dirty, that's normal.
If the oil doesn't look dirty. The oil isn't doing its job or something else is really wrong.

My relative had a Dodge Colt in the late 80s and early 90s and ran nothing but some generic oil and Fram filters. The oil looked almost like new even after 3000 miles. It look more like light iced tea color than the apple juice color of new oil, but that was it -- it was still somewhat transparent. Then he found out the engine was really messed up inside. The oil wasn't doing its job of suspending or carrying away contaminents.
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