dadgummit

Lately whenever I start my jeep I get a noise that, after reading many posts, may be the notorious engine dry-start knock. It starts about 1-2 seconds after I start the cold engine in the morning. It lasts less than a second then I never hear it again that day. It is not loud at all, with the doors closed and soft top up I can barely even hear it. It soulds like a high pitched ratteling sound.

I tried changing the oil filter to a Fram Tough guard from the purolator and added STP oil treatment and it made no difference. I am using Mobil 1 5w20 oil.

Can anyone with experience with this please give their opinion?

rinkishJK

Had this issue with fram filters.and I used the tough, and extra guard. Most don't, and one of my friends the fram fixed his, but for me no. So I use a mobil one filter now .209 . The stock size is 102. The 209 is the longer version, which has more "filter", and holds a lil more oil. This is all from the company that makes the filters for mobil one.since I started using this filter no more startup knock. It has an anti drain back valve. Give it a shot.

yrubuggin

http://royalpurple.com/street-thunder.html

dadgummit

Thanks, Did you have the same noise and this fixed it? Is it really that much better than the Mobil 1 Synthetic I am using?

yrubuggin

I am an outside sales rep. for an auto parts supplier, so I get to see all of the gimmicks (and have to answer for them when they don't live up to the hype). Royal Purple has quickly become the oil of choice with so many of my high-end shops. I had one shop show me pictures of a trophy truck's motor after they tore it down. They assumed everything would be toast after the truck ripped a whole in its oil pan and continued to drive it to a safe spot about 5 miles from where the damage occured. The motor was absolutely fine upon inspection. That is why they took pictures, so they could show their customers why it was worth the extra investment.

hurley84

Hey there guys- I am a long time member, but a new poster, so sorry if I did this wrong.
I have an 08 Jk and I had the same knocking noise at 40k miles, so I brought her in and they without even given me hell they replaced my engine. New engine has about 1k miles on it now and no more knocking.

ryanmauser

Ams Oil filter fixed the problem when nothing else would. Tried mobile 1 oil and filter, royal purple, you name it i tried it. I was so impressed with not even hearing a hint of a knocking, that I have since switched all fluids to Ams Oil. Most simple fix. You'll hear lots of opinions, but in my case Ams oil filter, all on its own did the job.

4wheelnD

I also had the knock when I bought my 09 with 19k miles on it. Firs thing I did was drain the oil and refill with mobil 1. Presto knock gone. Synthetic oils are worth evry penny!!!

yrubuggin

Before this thread turns into a "brand-bashing" free-for-all, I think you stated a very specific issue and asked for an opinion on a fix. The problem you are describing sounds like a lack of residual lubrication after the oil has fallen away from your valvetrain after sitting for a while. I don't believe you have a mechanical issue because it would continue after the couple of seconds you report it takes to go away. The reason I suggested Royal Purple is because it has a higher zinc/phospherus content than most synthetic oils. Zinc/phospherus additive packages in oils have some limitations(more isn't always better). Amsoil has a similar additive package, so it is another alternative. Mobil1 has a lower content because the API has specified a lower content(they are concerned about catalytic converter failures). Don't get sucked in to using a over the counter additive like Lucas or Rislone, etc... they will change the additive package that was chemically engineered to be in the base oil you are using(you could actually be ruining the oils effectiveness). Hope this helps, I know how confusing these discussions can get.

JKlad

Yep, I agree 100% here!

Because zinc & phosphorus damage cat converters & reduce their life the oil manufacturers have been pressured to drastically reduce the amounts of these additives over the past 10 or 15 years in the US (which has strict emmissions and mileage standards) in order for their oils to achieve API certification to the latest standard. Problem is that this, in combination with the move towards very low-viscocity oils in order to achieve slight gains in fuel economy has resulted in many motors experiencing increased rates of wear.

While roller-cam motors like the JK's V6 aren't affected as badly, these modern thin oils low in anti-wear additives are particularly damaging to older-designed flat tappet motors which is why several manufacturers including amsoil & Royal Purple still offer certain grades with higher levels of zinc & phosphorus still in them & simply forego attempting API certification on these. Sure people will say "ah, but with modern high-performance synthetic oils with superior film strength you no longer need these old fashioned anti-wear additives as these new hi-tec oils are far less prone to shearing under extreme operating conditions", but the reality is that even basic cheap non-synthetic 5W20 API certified dyno is still thin & without these additives without the much-hyped benefits of expensive full synthetic.

Where I am while the high-end full synthetics all tend to all carry the latest API certification regarding zinc/phosphorus levels and low viscocity for fuel economy, the majority of higher viscocity semi/non synthetic oils for older model and "higher mileage" motors still have reasonable amounts of zinc & phosphorus in them & don't attempt to qualify to the latest API standards since being in a non-us market these API standards are not compulsory and tend to be used more as a standard for brand new vehicles sold here of US manufacture (or with US manufactured/designed motors such as GM vehicles made here) only.